REDUCED POWER! (GM Intermittent P0641)
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- čas přidán 14. 03. 2022
- This 2010 Chevy Impala has a very intermittent glitch that puts the PCM into REDUCED POWER mode. Quite annoying.
Each time it throws a P0641 - 5V Reference #1 Circuit code.
Several shops tried to figure it out, but no luck.
Let's use scan data and the PicoScope to see if we can catch the glitch in the act, and then find the root cause.
THINK TOOL PROS:
www.amazon.com/dp/B08XXWHQVJ?...
Enjoy!
Ivan - Auta a dopravní prostředky
Ivan: "So many possibilities, this could take forever!"
Also Ivan, 5 minutes later: "Got it!"
👌😅
A simple cable support bracket not secured and unprotected wiring caused so much grief & I guess significant cost as the vehicle was seen by others, and parts replaced. Ivan fixes with the famous fix all items: duct tape and a cable tie, as good as no parts required! - NOW THAT IS PRICELESS! 🤣🤣🤣🤣🤣🤣
I'm not gonna lie, I feel cheated when is not bonus footage. Hahahah 😁
Perfect! Sometimes these intermittend faults can take forever to find!
Brings a whole new meaning to wiggle your harness. No parts required, fixed it again!
You are an absolutely Amazing Diagnostic Technician. As a Semi Retired Master Tech, I watch every video you post and learn a little something from them all. Thank you for taking the time to record and share them with us.
Glad to hear that you find the vids helpful! I'm learning new things on every diagnosis too 😁
don't make his swell up too much 🤣
The real key is when you accelerated the problem occurred. That means it's probably a wiring issue in the engine compartment from the engine/transaxle shifting under torque.
Probably worn motor mounts as well.
Great diagnosis and repair.
It's a little surprising that the previous mechanics didn't look closely at any wiring harness "rub spots" because even without a scope, one could've spotted an exposed wire.
Hopefully more and more professionals watch channels like yours to pick up tips.
Thanks Ivan!
90% of these shops are parts changers and that's why these channels get so much attention it shocks people to see them investigate and fix a problem.
not many of them are good at electrical, nor do many have the experience. it's been that way for many years, there was good mechanical shops, then there was good electrical/electronics related shops and it's rare to hit one that can handle both, let alone more than one or two top notch techs per shop, when you do they're so busy they start getting sloppy and missing things. 😖
Some time ago I had a Chrysler Valiant (Australia, 1966‐7 6 cylinder model) with much less complex wiring loom, but had an intermittent high on the temperature gauge. The wiring loom was held by a surrounding metal clip on the valve cover, just beneath the oil filler cap, which, with a small quantity of engine oil softened the insulation. This, with normal engine vibration, wore the insulation off the wire to the temperature gauge, causing the intermittent 'high'. The fix was exactly what you did, using plastic tape with the adhesive removed (by solvents). A few turns, and tied together... I could have used a scope then, but a multimeter was effective, as a scope in those days was much more valuable than the car...!
typical Chrysler/Mopar product, they've always been wiring nightmares. in fact they pioneered it. 🤣🤣
@@throttlebottle5906 Yeah.. Although the old Chrysler Valiant had done nearly 200,000 miles, and most certainly scrap now (plenty of steel in those days). As for wiring, surprisingly the 'nightmares' came in the more sophisticated wiring arrangements, where attention to the detail of their placement became crucial to reliable operation. Sometimes, when mechanical work is done, and the wiring is 'moved around', it can introduce an intermittent fault that never existed in the original manufacturer's configuration...
Thats the reason you should always secure the harness back to original hold downs , i carry loads of various clips just for this purpose.
zap-straps work great, aka zip-ties, use two or more of them combined, first one or more as standoffs and a final ziptie to hold the loom to the previous.
Excellent diagnosis and repair. I love these types of who done it videos.
Nice fix! Keith wiggle test works well when you have the scope out and see the drop outs! Nice video!! Many thumbs up!!
Way to go!!!! Fast and to the point! The ECM must have a really robustly-designed 5V supply. It could have easily been badly designed and would damage the ECM every time the wire went to ground. I've worked on stuff like that.
The newer computers especially from 08 and up seem to be pretty well hardened against damage from shorts and voltage spikes/surges, especially the drivers in the computers. And since everyone started moving toward CAN bus and the cars have so many modules in them now, I just wish the rest of the computer modules on the network were as resilient as the ECM/PCM modules were. If I'm remembering right, I think CAN supports up to 40 modules on a network at 1Mbit/sec. I think that's why companies like BMW started using FlexRay, because I guess a 40 module network wasn't enough, they needed 64 Modules at 10Mbit/sec. Pretty soon your gonna need a network engineer to fix your car.
Has a current limiter that only allows maybe 2 to 5 amps of current, whatever is in spec of the wire. It has to ramp up current in order to save on excessive heat when its not used but when the MAF sensor heater starts using more current, the PCM can supply that without other sensors dropping out.
@@jtjones4727 Fixing software glitches like windows engineers.
@@jtjones4727 perhaps they just use simple 5V linear regulator per channel, with short circuit protection and have a AD -converter line of FPGA (main chip) to measure voltage?
Ivan, great job! I was just looking at a two channel pico scope this morning. Now I'm going to have to go look again just to entertain myself. Everytime you find something like that you got to figure you really got lucky, but in your case you seem to get lucky a lot more than most of us. With St. Pat's day coming up maybe some of us will catch up with you! Ha! Thanks for Sharing!
Nicely done Ivan. Super cool to see you drill down to the 2mm break in the insulation to find the problem! Thanks!
Awesome to have found the error by essentially spotting the stressed harness with the scope running. Great as always, Ivan, and thanks!
Ivan, You are the man. Your patience and logical thinking make you a great diagnostic wiz! Glad you found it without moving the harness and “fixing it” but not replicating the problem against. Yep. Need a scope! (And the training to use it properly)
Another case where a wiring diagram leads you to where to look and the scope easily picked up the problem. Great job Ivan!
Another great NPR Fix Ivan! Thanks for taking us along. Cheers!
Ivan, you’re a a magical mechanical wizard that I am truly beginning to believe is from another planet. Yet another NPR fix.
A good electrician always plumbs wires in a "relaxed state (be it household, auto or otherwise) with few exceptions for exactly that reason. Chaffing, splitting, arching, ect..... are less likely to occur without tension. Great vid, Ivan!👍
Excellent presentation and detail. I really enjoy watching how you solve the issues, by following the circuits. I follow these as if I were doing the diag, and had a coach running me through the checklist..... lol. It's ALL a learning experience, and for that I thank you!
Hey Ivan, That was a smooth diagnostic. You make finding wiring issues easy... which it ain't. I just had a gem of a job that I thought you might find amusing. I got a call from a good customer, a farmer who lives out near Weikert, PA (not that far from you). His problem was a crank no-start with his 2019 Dakota. Since he's a good customer and a nice guy (he lets me hunt his place) I told him I'd check it out. So, when I got there the first thing I wanted to do was a quick visual (everything looked good... he maintains his stuff) and a scan. That's where the problems started: no internet, no cell reception, no way to get to Auto Auth... nada. So, the short version... I did not have an Autel 12+8 bypass cable at the time and, for that matter, didn't want to charge the guy an extra two hours to rip his console apart to find the security gateway module, it was a wasted trip. Fortunately he has access to a trailer so he could bring it in. Just another obstacle to be aware of.
It’s a pleasure watching you work. Great diag job.
You inspire me Mr. Ivan to diagnose the problems before making decisions on buying parts. As a backyard mechanic, gaining reputation to getting more people to see me instead of them paying alot in expensive shops.
Yes only buy parts AFTER the diagnosis! :)
Ivan...you always make it look sooooo easy !!!! WOW you have impressive abilities and skills. I just love your videos. You are an addiction THANK YOU !!!!!
Good methodical diagnosis skills seen at it's best. Job well done.
Without watching it I assumed it was an APP issue just because it was going into limp mode on acceleration. These era GMs were absolutely notorious for throttle pedal failures. However, I would have assumed the module was the culprit and replaced it, only to have the problem come back later. Nice diagnosis!
I heard the electric throttle body dropping out literally when you found the short. This is top-notch high quality troubleshooting and I have learned so much from you this is why the car could not go any further just because of that throttle body being affected by the short occurring on That Metal crazy crazy crazy wild......
Hey ivan, this is first comment i make on your channel, i find you weeks ago and now i am like watching 2 or 3 videos of you everyday! Good job sir, iam an automative electrician and going to do outside work like you soon ^^ anyways, there is an option on the picoscope called alarm, its for this intermittent fault like voltage drop, the software will beep when it goes down the voltage so you wont need to keep looking at the screen while touching the wires especially when working alone or under the hood, that function in picoscope is really helpful. Keep the great work ivan
Very cool! Will have to try it 👌
IVAN, AWESOME approach and thought process always learning from the best thanks for sharing.
Great work as usual 👍 I had a 2013 Silverado with the p0641, p0452 fuel tank pressure sensor and p0107 map sensor. Ended up being the FTP sensor. It was shorted so badly that it was pulling down the 5v reference.
Nice attention to detail Ivan!
Just started watching, going for those rough wires Ivan pointed out !
My problem was a bare spot rubbed thru the wiring harness at the steering shaft boot. You saved me a ton of searching and buying parts and sensors just throwing 💩 against the wall to see what sticks. May God bless you many times above what I am able and let me most humbly THANK YOU! 💯💪❤️
Much appreciated, great find on the harness!
the power of the scope but more powerful the visual inspection lol :) great job Ivan!!
This was incredibly helpful!! I had the key turned but not on and started wiggling wires and found which ones triggered low power mode.
The scope for the win again! What's fun is when the engine torques under accel, a wire shorts out and the engine dies.
Good work Ivan! Another one fixed!
Hope that Mercedes SUV from last week is still going. Still can't get over the rear window washer soaked that unprotected CAN bus connector down in that well and it became a no start! Poor design!
While it might look simple on the video, I know that it is not. Nice job finding the issue. It could have been under the car too which would have made it much more difficult. I can't imagine how difficult it is to diagnose these cars out on the street or in someone's driveway but you do it and I am so impressed.
Great explanation! I’m excited to go look and see if I can finally fix my Malibu!
good call Ivan.. once again you find and fix the problem! Nice.
So visual inspection should include older repairs and newer tiewraps somewhere in the engine bay., good job done Ivan..
Tricky one Ivan, you did an Excellent Diagnosis on this one.
Ivan
Great video, diag, and fix - thank you!
Paul (in MA)
The "Doctor" is really in! Awesome work Ivan!
Great diagnosis Ivan. Good find.
Fantastic logic Ivan. Im so impressed 👍👍🇬🇧
Ivan has given more life to an aging car.
Awesome find. I had a similar issue on a 5v ref on a Saturn Vue with the Honda engine. ( Yes another Saturn) LOL Like you used my scope. Found it was the A/C pressure sensor connector. I agree when you find the problem quickly. No better feeling.
Great job, Ivan. Another one for the archives,
A good thought, wouldn't hurt to go in and check your wiring once in a while. No rubs, no rips, no errors!
great detective work there ivan,, job well done!!
What I like about PHAD is they don't blast you in the beginning with loud commercials.
What I like (aside from Ivan's Ninja Diagnostics)
1. No click-bait titles
2. No annoying music.
3. No unnecessary graphics.
4. Does anyone enjoy watching cars go up and down on a lift??
5. No repeating himself 3 times.
6. Only has legitimate criticism.
7. Does not describe things with first grade adjectives.
8. Shop is neat and orderly
9. Does not need to raise his voice to be heard or understood.
10. We are SO lucky to have a person like Ivan. He is truly amazing!!!
@@rjedro Thank you for the feedback, Bob! My goal is to present only the relevant stuff and not waste my audience's time :)
Nicely done Ivan.
Nice recovery. Just shows how many hacks there are in wrench land!
You're one badass dude on electrical...
A great case study quick NPR fix again . You mentioned the 5 volt reference circuit source , can these supplies tolerate short circuits it has some intelligent monitoring as you showed by it ramping the current back up when you put the extra load of the test light to ground . I was wondering if it has some kind of short circuit current protection for the source from dead shorts to ground . It was generating a 5volt reference code so it was detecting the voltage dip .
Good catch! Before I could reason a bit, I immediately thought of a broken 5V ref wire but, like you said, it would set sensor codes.
Also a broken wire usually stays broken, unless it's a Malibu with broken copper strands inside intact insulation haha
@@PineHollowAutoDiagnostics LOL, yes 🙂
Great job Ivan, would you have seen the same results using the graph on the Thinktool, just purchased my first oscilloscope only a cheap Hantek but a good starting point I think until I move on the expensive Pico
Yet another example of sloppy mechanics being in there before you. Great diagnostic work
Many many thanks for sharing! I will definitely watch and subscribe!
That feeling it's priceless indeed
Awesome!!...good one Ivan 👍😎
I find it funny that some mechanics and DIYers look at wiring supports or tie downs as optional. Many people don’t respect that wiring actually runs the vehicle. Lol. I’ve actually heard people say “ahh I don’t care if something electrical doesn’t work, I just want the car to run again.” Hahaha. People! Your Car Won’t Run Without ALL That Wiring! Pay attention to harnesses! 🤣 Great Video as always Ivan!
Well done Ivan 👍
I remember getting one of these as a rental in Florida years ago (when I flew there from Australia to see a shuttle launch). Was one of the worst cars I’ve ever driven, horrible sloppy boat of a thing. Took it back to the rental company the next day and swapped it for a Sonata which was a massive improvement :)
All of that because of "collateral damage" from a previous DIY or mechanic. That is one reason why customers seem to always have another problem in the future not to mention, the original routing and design of parts, wire looms, etc. get changed and then all of that OEM engineering is at a disadvantage causing strain, rubbing, chafing and much more.
Watch your six mechanics...gentle with other peoples private property and be less invasive.
Agreed
another mystery solved
Unbelievable good found and fix.
In the last week or two, I've watched ALL 170+ of your 'No Start' vids in the playlist. Excellent stuff. Ivan, I wish you would buy one of those super cheap "DIY scopes" on ebay (DSO138 or DSO150, ect.). They are only $30 or so, or you can get the "kits" as low as $5, but you have to solder them yourself... I think it would be really cool to see you put these to the test and see if they are viable-- because they seem to be fairly useful to me, as far as I can tell.
Wow that's a lot of videos! Glad you are finding the playlists helpful :)
@@PineHollowAutoDiagnostics Yeah, I've been binge watching them non-stop; I had finally broke down and bought a scan tool (I got the xtool D8). It's like night and day now with doing diag-- I've been shooting the parts cannon for years and didn't realize it. lol. (It has always worked out for me though- luckily). Now I just need a scope; I can see how absolutely necessary it is. I'm hoping that one of these cheap $30, one channel, DIY scopes on ebay will get my foot in the door for now. Or I may just get the $235, 2 channel, Pico.. Not sure yet-- I'm still researching the cheapest step for now.
Had similar problem on shared platform Lacrosse my wife with baby in back, caused an abrupt road departure onto the shoulder. The Buick service manager acted like he dgaf when I told him to submit it for recall. Sold that POS right after it got fixed.
Ivan is the man 👍👍👍👍
Great diagnosis
Question.
On my 01 Corolla, I had to replace the cruise control switch because I broke it after I installed my hand controls in the car and they initially were too close to the steering wheel. I found more by accident that the steering column and wheel were from a 2000 Rav4, but everything worked except the cruise when it was told to resume or accelerate by the cruise module.
The cruise does work, it sets and releases fine, however when it is asked to accelerate the car, it will try to but it will release after 1 second of attempting to do so. I am thinking it is a defective unit where the motor in that does not want to increase the speed. It will set the speed and hold it, and release when it is told to by me or by the system. I wonder if it is possible to scope the motor to see what it is doing electrically. My pico is the 8 channel plus I also have the 4 channel unit. I use both the version 6 and version 7 depending on what I want to do with it. Any way to do that.
Hello sir your video definitely was helpful did wrapping the wires actually solve your problem? I have the same exact issue going on
Not sure how long your actual diagnosis time was but amazing. Hope you are earning a good living as there are not many techs out there with your instincts.
Very well done!
nice job good fortune on this one
NPR repair! Great diag. and fix!!
Thank you Ivan
Great repair brother. I’m glad it was relatively easy to find. 👊🏼
Doesn't reflect very well on the various workshops it went to previously.
@@johnmccallum8512 to be fair it is very hard to find diagnostic techs out there like Ivan let alone finding enough of them to put one in every shop. Most reputable shops will tell you that they can’t fix it even after trying and will recommend further diags at another shop. The ones you have to watch for are the ones that say they fixed it or have thrown the parts cannon and really didn’t fix anything
@@johnmccallum8512 Not necessarily...they just lack the proper tools and approach :)
@@PineHollowAutoDiagnostics Then I will just say this. If motor manufacturers continue to put so many computer parts in their cars then they should be training the Techs to diagnose their systems properly.
You da man . Nice job as always.
This man is a genius of auto mechanics and computer diagnosis......
I think he may be the best automotive diagnostic technician in the United States.
Wow. Great Video as always..
good visual inspection and wiggle. wtg
Very good at what you do 👍🏼
Top work!
That was great. Nice find on that.
GREAT WORK
I have a 2010 Chevrolet impala lt flex fuel 3.5 v6. I have been without a car since October. First my car started going into limp mode, it would stay running but when I hit the gas nothing happened. I took it to 2 parts houses and they both told me something different. I borrowed a obd2 scanner and every time it would give me a code and I would change said part, another code would come up days later and it still drove the same (limp mode) or rpms higher than normal. Since October, I have changed Map sensor, MAF sensor, camshaft sensor, wiring harness for the camshaft sensor, oil pressure sensor, VVT solenoid, changed the oil and filter, ect. It has always cranked and ran fine until recently and it wouldn't start, even though it has good power. Now its giving me a code (U0100) Lost communication with ecm/pcm "A" ..
I'm not sure what the A is but I did have a code that came back camshaft position sensor open circuit "A" which I changed the sensor and harness. I dont know if I need a Ecm/pcm or a TCU since they both run hand in hand. I truly appreciate any advice or recommendations you can give me. I have done all the work myself with the help of a obd2 scanner and Google. I'm out of options here. .
You are fast 🤘🏼
Nice detective work!
You are very good but that also means MOST shops are dumb…
Nice job motoyam
When the wiggle test doesn't expose the issue I start unplugging and inspecting connections
Wow man that’s good detective work
I had a problem with my car. Dealership couldn't fix. Never went back to that place. I finally found the problem and fixed it myself.
Great job
Great video well done bro
Well done great fix in gold time