How to Diagnose a No Crank, No Start Chevy Avalanche or Silverado 5.3L (Blown 20a PCM B Fuse)
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- čas přidán 5. 07. 2024
- This is how I diagnosed my 2005 Chevy Avalanche that stopped running while driving, and left me with a no-crank condition. Turning the ignition/key didn’t activate the starter, and didn’t turn over the engine. I diagnosed it as a blown 20a PCM B fuse in the under hose fuse box. The most common cause for this is a dying fuel pump. See comments for extensive discussion on the topic.
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Jeremy,...I'm a dealership tech, listen to LHMex, I see this stuff daily. Step 1 you turn the key to ignition and you don't see the gear selector highlighting what gear it's on. That tells you pick is not communicating. Step 2 check 20 amp pcmB fuse. That fuse feeds the ecm,....and the fuel pump. Most likely cause, is a fuel pump, very rarely would it be the pc. My $$ is on a fuel pump.
Rusted Horsepower - good info! I’d better recheck that wiring diagram, because I hadn’t seen the fuel pump circuit when I looked at the diagram. I also only had some screenshots of it. I’ll try to dig up the whole thing!
@@WiringRescue GM is funny that way, if you look at power and ground schematics for the pcm. it shows 2 circuits from that fuse to pcm only., BUT if you look at "wiring systems" schematics it shows more detail, within the under hood fuseblock it feeds the "Load" side of the fuel pump relay. If you jumper your fuel pump relay, the same way you did your starter, it will run continuously, then pull pcmB fuse, and it will quit. This will prove the circuit/fuel pump is fed by pcmB.
Rusted Horsepower - great info! I’ll dig up that diagram today and take a look. It may be worth noting that I’ve replaced the fuel pump and sending unit about 3000 miles ago because the sending unit was rotted and leaking.
hope you can help me :)
im having same problem. pcmb fuse is good.
theres 2 wires that are supposed to be hot for ignition to work. one leg is dead makes truck start but doesnt need to be connected all the time same leg runs a/c blower motor
installed new ignition switch same issue. all relays seem to work. when i jump the hots together it starts fine.
transmission keeps losing 1 and 4 maybe another issue
@@ronaldbottoms3272 LW?
So I did an pcm swap and had to get a shop to extract a bolt from the plug on the pcm and he got it out and put it all back together and it wouldn't even turn over so I had to pull it home. I get it home try messing with it and still nothing.. I get on CZcams and research and found this video so I went out there and looked at the pcm fuse and it was blown just like yours I put another fuse in and she cranked right up. Thanks for everybody on CZcams, y'all are a big help. This video was so precise and it fixed my problem. Thank you and hope you receive as many miracles as you give.
That’s fantastic! I’m glad you were able to get your truck running again! Thank you for watching, and for all the kind words!
I was trying various things from other videos and then I watched yours and followed along and I had the same problem blown PCM fuse. My fuse blew when I was cranking with a low battery. Thank you !
Excellent! Keep some spare fuses in the truck for when it happens again! Good luck and thanks for watching!
I've been stranded for fkn HOURS!!! 😫 scan tool not reading! Tightened my starter wires even more! Tried to rig it up and glad I saw this video! My fuse was blown as well that exact fuse! That freakin 20A little B**CH! Stopped my WHOLE FREAKIN DAY!!
That’s exactly why I made the video! Glad to hear it helped you out!!
@@WiringRescue I’m having problems with the fuse PCM 1? Any tips my truck won’t start at all.
im barley seeing this rn because my truck was doing this problem and man you saved me a lot of money your the man fr thank you🙏🏽🙏🏽
I’m happy to hear the video helped you out! Thanks for watching!
You helped me big time! I solved my no crank issue.
I have a 2007 Chevy Express van with 4.8L engine. It exhibited exactly same symptom as you - NO crank, NO underscore selection light under PRND32.
Everyone told me it was the battery, battery, battery, and may be a fuse, relay, neutral safety switch, solenoid, blahblah but I wasn't convinced. Because it was working fine week before. When I heard you mention OBD2 reader not communicating, I thought I'd try the same. BINGO. It wasn't communicating, just like in the video.
It was the same PCM B Fuse (20A).
Thank you. I would send you a keg of beer if you were near me.
😂 I would happily accept a keg of beer! Seriously though, I’m glad your issue was at least temporarily sorted out. Keep extra fuses in your truck and an eye on your fuel pump. From what I understand, the fuel pump is the most common reason for this fuse popping. Good luck - I’m cheering for you and your van!
You just saved my life! I have spent 4 hours trying to figure out wtf is wrong and I watched this video and it was my PCM 1 fuse that was blown - thank you!
Hell yes! That’s fantastic! Keep some spare fuses on you for next time!
@@WiringRescue or use a circuit breaker until you find the issue which many times is the fuel pump drawing too many amps.
Man the wire jump saved me from being stuck.. appreciate it
Excellent! I’m glad the video was able to help you out!
@@WiringRescueany tips how to fix the crank fuse one? I’m getting no power whatsoever I even changed the fuse. That’s my issue with my 05 Silverado o believe
..thank you for your "try this, then that" style of troubleshooting. You did find your problem.
This video will help many of us to be more comfortable with troubleshooting.
You just saved me from being stranded in the local ER's parking lot all day. Key on, jumped the starter relay, and she fired. Nfi what's wrong yet, just got home; but I know where to look now.
Heck yes! You’re a rock star! Also - sorry to hear you were at the ER. That is rarely a good thing. Hope all is better now, and good luck with the truck!
Good evening. I just wanted to say Thank you. My 03 Escalade was running and died in my driveway and wouldn't restart. With the help of your watching your video and changed my 20 amp Pcm fuse it fired up . Again Thank you .
I’m happy the video was able to help you out! Be sure to keep an eye on your fuel pump in the future, because it is often the cause of these burned fuses.
Thanks for the video I was just stranded on the expressway and this just got me back on the road and headed home.
This is definitely the coolest thing that has happened to me this week. Thanks for commenting! I really am glad that the video was able to help you out. Also - See the other comments here about the fuel pump causing this issue. There is good info here from other people! Good luck with the truck!
This is what it’s all about nice job
Thank you sir. Very informative for someone with minor knowledge of vehicle stuff
Thanks Rob! I appreciate it.
This video got my truck running again thank you man you are a great trouble shooter
Heck yes! Keep some extra fuses handy and an eye on the fuel pump! Thanks for watching!
Thanks for this video. After 2mths fighting with this issue..the stupid ass fuse was the problem...I swapped out the starter, batteries, ignition switch and the main relay fuses..all for a 10cent fuse..
At least you didn’t give up, and you figured it out! That’s awesome! Congrats!
You’re the fn man my man! I had the exact same issue with a GMC Yukon 2004 and I knew it wasn’t the starter not the relay the problem, exactly what was wrong with my truck , same fuse , pcm B, thank you very much!
I’m happy that the video helped you out! Now you just have to figure out why that fuse blew! I’ve heard the fuel pump slowing dying is the most common reason. Good luck!
Great video. I’m having all the same issues. I never checked the PCM fuse and I guarantee that my problem. ODB reader wasn’t connecting either. Definitely going to check it when I get home. Again great video!
My 20A pcm fuse was blown when I checked it like the video shows!!! This saved me a lot of cash!!! Thank you very much!!!
It had an intermittent no crank no start. I don’t know how it ever started with a blown fuse......isn’t that impossible. Tell me......
TODD J. L. ALLEN - It won’t start with that fuse being blown. Maybe it finally met its match and popped the fuse this time? It seems that dying fuel pumps are the most often reason for this fuse to blow. Keep an eye on your fuel pump, or if you know it has a ton of miles on it, you could throw a new one in there and hope for the best!
Thank you Soo much. Exact same thing happened and now I'm back in the road!
Your welcome! Keep an eye on your fuel pump! It may be on its way out!
I just picked up a silverado that had this problem your video save me $$$$ and for that I much appreciate it
The fuse blew for a reason though.
Thank you for this video I have a 2005 avalanche, same issue but it happen on a Sunday leaving Walmart and again on Wednesday morning leaving for work. I saw this video and literally took out my pcm relay and put it back in and FIxed!!
Now I am going to purchase a new one but it did fix the problem for now. I even switched out my ignition switch and that didn’t work. One mechanic even mentioned it may be my anti theft . But once again YT saves my ass and money!
Thanks for watching the video! I’m so happy to hear that you were able to get your truck working again.
This was the best tip ever and just helped me immensely!
I’m glad I could help you out! Feel free to share the video! I’d love more subscribers. :)
Dude u are a life saver ,thank you!
Dude, thank you so much. I learned a new way to check fuses.
Excellent! I’m thrilled that the video helped you out!
This video saved me so much money time and so much more thank you
Thank you for watching! Glad it helped!
Thank You, my fuel line's 20A fuse was blown, prolly saved me 1000s lol =D
Thank you so much for the tip I got my Denali 04 running again
That’s fantastic! I’m glad the video helped you out! Thanks for watching!
Yo dude no somethings that's all I'm saying my truck wasn't cranking watch my boy on CZcams n Bam!! We have lift off 2 thumbs up bro
That’s awesome! I’m really glad I could help out!
After I changed my fuel pump I was having no start issues. Just tried to jump it and nothing. Watched this video dc went and changed my Ecm fuse in the same location and yayyy my truck starts again 💪🏾💪🏾💪🏾💪🏾💪🏾
Heeeey! That’s absolutely fantastic! I’m glad your truck is back on the road again! Thanks for watching the video!
Thanks !!!! I finally figured out that's why my blazer won't start, it was this fuse
Nailed the problem with the battery bypass suggestion...once the truck was running I could access the computer codes and diagnose the Mass Airflow Sensor as the problem causing the rough running/stalling. Thanks!
Excellent! I’m thrilled that the video is helping people out! Thanks for watching!
A better way to check those fuses is by using the Continuity setting. Not all fuses will have power, until you turn the key on.
Is it safe for your tester, to check continuity on a hot circuit?
Precise and to the point nice work!
Thank you! I appreciate you watching my video!
This solved my problem. Thanks!
I’m thrilled that it helped you out! Thanks for watching!
Helpful video. Mine turned out to be the PCM 1 fuse, the 15 amp right above the 20. Come to find out, it's either the fuel pump or mass Air flow sensor causing it to short.. Both I just changed out prior to the fuse blowing. Go figure!!! I'm sending them both back. Good thing I cut through the floor, under the back driver side seat. I'm not dropping that tank. Not on a 2003 Tahoe Z71. Getting my fuel pump out will be a breeze to take out and send back. This video sure was helpful though. Thank You!!!
Thank you for making this video very helpful
I’m glad it was able to help you out! Thank you for watching!
Lmao now Iam thinking. I don’t know what im thinking! That’s where we all get to when shit ain’t working
Lol. It has pretty much become a way of life at this point. Thanks for watching and sharing in my automotive mysteries!
Great Video Extremely Helpful
I’m glad it helped you out!
Awesome video thanks for sharing
Thanks for watching!
Thank you brother, very helpful!!!
Thanks so much for your bomb ass video,it saved me!!
I’m thrilled that it helped you out!
THANK YOU SO MUCH FOR THIS. my dads 2003 avalanche hasn’t been driven since november and sat in -40 celsius all winter!! if i replace the battery and nothing happens still, i know what to do next! thank you so much
Good luck! I’m cheering for you!
Brilliant.......I have a hummer h1 with two side post batteries wired in series....always a pain.
DrStickyTits - right?! I hate side post batteries! Why do they even exist?
Thanks for the video!!
You’re very welcome! Glad you liked it!
Hey man thanks for the video I havent checked my pcm I blew a headgasket took apart the motor and put it back together the motors spinning i did the jump wire trick but not the jumper cable so ill try that next any other pointers you could give out thanks again for the awesome content
Thank you for this.. now I'm going to try this.. my 2005 avalanche is doing the same thing. Hopefully it's just the fuse
You’re very welcome! Good luck!
If your original brake lines haven't rusted out yet and you get to where air is introduced into the ABS controller to make a brake line repair, you will need a tech 2 scanner to do the automated bleed operation on the ABS. I had a guy try it with a $10K Snap On scanner on my '02 Avalanche and it didn't work. So I got the tech 2 scanner. Also there are storage slots on the fuse panel to hold a few spare fuses if you wanna keep a few handy there.
Didn't know where to look, battery? starter? relay? This is a great vid. thanks...
Happy to help and good luck with your truck!
Always check the simple things first.
Cool cat conveys clues! I will watch this again. Oh, and subscribe. Thnx
You rock! Thank you!
Appreciate your video! Helped me out
I'm really happy to hear that! Thank you for watching!
Great video. Thank you. 👍
Im glad you liked the video! Thanks!
Thank you this really worked!!
You're welcome! Thanks for watching the video.
Very helpful
Leo Steinman - thanks! I was hoping that it would be!!
Thank you from another older shade tree
Happy to help!!
Great video. When you could not read the obd port, I was thinking your cigarette lighter fuse was blown. Think from now on, if the car is 96 or newer, I am going to grab my scan tool first.
Yea! Diagnosing a car can be sneaky sometimes! I wish I checked fuses first! Ah well, next time!
Thank you for your video
Thank you for watching the video! I appreciate it!
wow...huge respect....280K Miles!.........American vehicles do last longer.........unlike popular belief!
General Motors V8's are quite good! Plus they are cheap to replace when you run out of oil pressure and send the connecting rod through the block.
Good job
Thank you!
Well that's one thing I'll check I didn't use a volt meter to check them properly. So odd that fuse can cause that kind off issue but makes sense. My truck is mostly dead dash bearly turns on and dies I mostly eliminated everything but never checked that fuse.
Is there a certain way you rigged up that wire to check the starter? I noticed it had a fuse on the end so I didn't know if that was necessary before trying. Thank you in advance!
Hello my friend I have a car like the one that you have and from the same model I have a problem with the backlight bulb does not work and when I checked all the things that can affect all in excellent condition but I doubt the piece but I do not know where it is and the electronic piece is responsible for if I put the stick of the transmission back to light up Backlight Can you help me, thanks
Thank you
Nice job! Hopefully the fuse doesn't blow again. Maybe some sneaky moisture in there? Your oil pressure is maxed out haha
I generally don't run oil pressure gauges in my cars because they only tell you bad news. Why the heck would I want bad news when I'm cruising in my car? In this case, I can't really avoid the gauge because the truck came with it, so I just assume the engine is fine.
I got the top post adapters and put a top post battery in my 03 Avalanche 2500. Also fuses do blow with age. I has a couple do that on my Escalade.
trafalga5136 - top post adapters are the best thing ever invented, or damn close to it! I wish sidepost batteries could be UN-invented.
I replaced my battery cable ends with REAL ones. I recommend everyone do the same.
Interesting issue with the Fuse, have you had any more issues that are Related and or did the Computer take a dump? Getting ready to go see what my '03 Tahoe will do, one day it just didn't want to start, turn key it's dead, jumped started nothing happened so l bet it's the Relay. Why is that relay even there, we never used them in the past. Things were so simple and easy to work on in the past. Gonna sell my truck and get an old one, lol. Thx for sharing!!
Awesome information!!!!
Carlos P - thank you! Hopefully it helps you out in some way!
Jeremy N Oh Yes Jeremy! Getting hooked with the LS engines and every little bit of trouble shooting solution helps.
Carlos P - LS engines are pretty fun. I assume you’ve seen the 72 Lemans 6.0 swap project videos I make?
Jeremy N Yes i have seen parts of some of the videos and i will be watching them. I have a friend here in Alaska that has one and is planning in doing a swap. I am my self working on a 5.3 that will go into a Ford E350 Shuttle bus RV and 4x4 conversion. Doing this swap the bus is going into a big diet.
Carlos P - that’s awesome. I have no doubt you’ll be very happy with the LS!
Im having this problem with my chevy so im guessing its that same
One as yours that i gotta replace?
Info on sticking wires into relay pin holes to start it?
exactly what is wrong with my 03, it won’t start, the car lights come on but soon and i turn the key the lights turn off like yours, i changed out my starter and still nothing, do you think it could be the key ignition since mine is broken?? the key won’t turn off all the way so i disconnect the battery
I need help.03 Silverado 5.3 cranks no start.fuel pressure 55. No spark injectors no pulsating.it has 12 vlts when key is on.ohms are 3 all of them.change cam an crank sensor..when I crank it it sounds good .don't know what else to check for
as a line tech of 40 yrs, electrical 101 ALWAYS check puses first with ANY electrical problem.. Good video ,though
Do you have the link for that volt thing I can’t find that one
How about doing a video on how to install holley fuel injection on a early model Chevy engine. That would be awesome thanks.
I just watched your video and I solved my problem just like you did. Thankyou! I wonder what could of possibly cracked the fuse considering it’s covered and never messed with. GM typically is full of electrical anomalies.
That’s awesome! I’m glad your truck is semi-sorted out. Apparently the fuel pump causes this quite frequently when it is beginning to die a slow death.
That’s funny. I changed my fuel pump about 20000 miles ago. It’s just recently would intermittently start and not start. When I removed the fuse i noticed it actually didn’t blow, but the plastic housing around the fuse cracked causing it to disconnect. Quite bizarre!
@@jthek2000 - that’s extremely weird! I’d probably just forget that it happened, keep extra fuses in the console and keep on driving!
Does it have have key on when u check fuses
Any update my Tahoe is doing exactly what yours was doing but the fuse wasn’t blown. Also it is intermittent. It also will lose power to trans putting it in limp mode where it stays in 3rd gear only and the abs light and other lights would come on randomly and then it will drive fine the next day. The ac wouldn’t blow cold once or twice during the issues but then would be fine the next day. I am wondering if you had anymore issues and if you ended up replacing pcm.
I sold the truck a while ago, and during the time I owned it, the ECU was never replaced. The owner after me did replace the fuel pump though.
Will this work for a 2016 Cadillac Escalade
So riddle me this. I have a 2003 Avalanche Z71, we had a big snow storm, I went out on Christmas morning and no crank? The truck ran the night before. I have had a problem in the summer for the last 2 years where if I used the AC or let it idle on real hot days I would get a no crank just like in the video. But if I opened the hood and let it cool 5 to 10 min it would turn over no problem. However, if I jumped the relay to start it the AC blew hot. Also, in the winter I had to let it warm up before I drove it or it would go to reduced engine speed and I would have to shut it off and restart it several times to make it run right. Now it turns on my scanner but it can't read the computer. No bad fuses and no idea where to go from here. Any help please.😢
In my experience, if there are issues connecting to the computer with a scanner, the computer is the problem. Car computers don’t need a whole lot connected to them for the scan tool to work and read engine data. You could always grab a reflashed pcm for a LS swap that deletes the VATS (vehicle anti-theft system) and plug in it to see how it performs. That would save you from spending a ton at a dealer - maybe only cost you about $125 ish? That being said - others here may have better methods of diagnosing your problem than I do!
I jumper the starter relay and now my cluster lights won't turn on or any lights inside .
Do you honestly have 75-80 on your oil pressure? My 03 with 220 k only sits at 40 lbs all day, everyday as long as I can remember and I bought it new. Motor burns no oil and has equal compression. Any thoughts?
Assuming the gauge is right, yes. But this truck was fairly crappy, so it’s also possible it was just lying to us. I have always heard from old school hotrod guys that you need 5psi for every 1000 rpm. So at 40psi, I’d think your just fine. Also - I generally don’t put oil pressure gauges in my cars because they just give me something to worry about. I’d rather not know. Either way - good luck, and thanks for watching the video!
What will make your truck power down to you have no throttle just a high idol
Is the cable from the battery to the little red box a fusible link?
I’m showing 12 volts at the battery, but only 4 at the red box.
What would be your next step if the engine didn't turn over when you jumped the starter relay fuse 87-30?
I would make sure that either 30 or 87 (likely 30) has power, and that when you try to start the truck pin 86 or 85 (likely 86) gets power. On my truck, I had the same exact problem and the ground strap had rotted off the starter. Replacing the starter was the fix. Good luck!
Lucky u!
What can I say, I am a guy that drives and works on crappy vehicles! lol
Wish you'd explain the 30 and 87 on the fuse jumping. How did you immediately know that etc..
I make tons of wiring videos, so it’s sort of my thing. Here is a video explaining it. I have many better, newer, wiring videos, but people seem to like this specific one because it is very basic. czcams.com/video/W2Mr2Zgv1Ck/video.htmlsi=EP7bcd8Z9qduCgBJ
Dang it. I just had (have currently) the same problem, but all my fuses are good. I tried to jump the starter fuse holes, and it started and ran, then died. Then I tried again, and it sounded like it was dying, and then it wouldn't turn over the starter.
Maybe it's my starter now, but I don't think that was it originally.
Igne 10a red little fuse keeps blowing when starting and driving , how do I fix
I’ve got an 06 Silverado 1500. My truck randomly shut off on me and I had my pcm replaced 3 times within a month. Do you think is a similar issue?
I think it is certain possible that this is your issue and you don’t have 3 bad pcms. The fuel pumps on these trucks cause all sorts of bizarre issues when they begin to die. I’d explore that path along with rotted ground straps, and see where it takes you.
What did you use to start it when you removed the relay? Some wire with a fuse attached? What is that called?
I just used a fused wire I believe
It's the fuel pump it's always The fuel pump except when it's fuel pump
b awesome - lol. This time, it wasn’t the fuel pump!
Lol
just watched this changed pcm starter key and tumbler still does it said screw it and put in a puch button start
I have a 2006 Chevy Silverado , I had some running around to do , I got back home , I had forgot to grab something from the store and I went to start my truck and it wouldn’t start it just clicked the lights came on but it wouldn’t start or crank . The next day I came out to try to start it and it cranked but didn’t start . Can you please help !!
You need to find out what’s missing, fuel, spark, or compression. You’re unlikely to lose compression, so you are probably missing fuel or spark. You’ll need to diagnose from here though, checking for each.
I’m having the same problem checked every even changed the fuse was not it
What fuse was it?
Don’t be like me and try to fix $hit yourselves. I put in a new starter and battery. Nothing. Checked the fuses under the hood and there she was. Busted 40A ING fuse. $5 at AutoZone vs $75 for a starter and $160 for a battery. Oh well. At least I learned how to replace my starter. She’s 20yrs old (1999 step side z71). She was due for a spoiling.
I think all of us have jumped to conclusions before and gotten burned. It stinks when it costs you $160 though! At least your truck has a few new fresh parts! Thanks for watching the video!
My 05 Tahoe did exactly that but my fuse isn't blown. Any suggestions
What caused the ING A 40 amp fuse to blow?
I have the exact same issue. Except PCM fuses are all good. All the fuses are good. Transmission just got rebuilt. Test drove it 8 miles then pulling back into shop "reduced engine power" popped up on dash then it shut off by itself. No idea what is going on man.
This happened to me ,dang ol fuse cost me a days work of 250 bucks
We’ll fuck me running , great video man
Thank you sir! Hope it helped you out! There is some good info in these comments too. Check em out.
Hey how can I change all four air chock struts?
I think 1A Auto has great auto repair video app for jobs like that. Download the 1A Auto app and have a look. Good luck!