Volvo 240 - Odometer Gear Replacement & Mileage Correction
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- čas přidán 26. 07. 2024
- A not-so-quick video detailling a step-by-step process for replacing the odometer gear on a 1990 Volvo 240. This video does not cover how to remove or reinstall the instrument cluster, only how to disassemble it once out of the car.
Also shown is how to use a very simple Arduino setup to emulate the speed sensor on the rear axle, thus allowing one to both test the odometer repair and verify correct action, and also correct for any lost mileage whilst the odometer was broken.
Volvo Owner's Club Forum Thread:
www.volvoforums.org.uk/showth...
Arduino IDE Download:
www.arduino.cc/en/software
(I used version 1.8.19, so you'll need to scroll down on this page to get the exact same one used in this video).
Chapters:
00:00 Speedometer Removal
04:36 Galvonometer Disassembly
05:00 Odometer Gear Removal
07:40 Checking For Debris
09:18 Debris Removal
10:15 New Gear Lubrication
12:10 New Gear Installation
14:49 Galvonometer Reassembly
18:23 Soldering Test Wires
21:34 Test Setup Equipment
23:29 Arduino IDE & Code
28:20 Arduino Connections
30:04 First Power On & Troubleshooting
31:22 Jumping Metal Connectors - Auta a dopravní prostředky
Excellent DIY video regarding this chronic problem. I’ve seen many videos on this topic and believe that this is the best. Thank you!
Thank you fella 👍
David - I have the same issue with the speedometer working but the odometer rotor just twitching and not turning. Have you found any solution to this. I am thinking that it might be that the UAF2115 chip is bad?
can you run 12 volts through a arduino uno?
You can if you use either the DC barrel jack or the VIN pin. Do NOT apply 12V to any of the other pins or it will cause damage.
I did everything according to your video, powered up the programmed Arduino, the needle instantly pegged at 120 mph and the odometer rotor in the center of the motor just twitches and does not spin. I verified that the gears are correctly meshed and the rotor can move freely. Any ideas? I’m stuck here. Thank you.
Can't say I've ever encountered this problem so I don't know a definite solution.
One thing that does spring to mind is if the odometer motor is a stepper motor, it is possible to drive them too fast - this doesn't cause damage to the motor, but does cause the symptoms you're describing. This would be the easiest to fix: just increase the delay value up from 1500 (see 26:55), if the speedometer begins reading a 'normal' speed and the odometer still isn't moving then this is not the cause.
The other question is: have you definitely any and all stripped teeth from inside the unit? It is possible for them to have fallen into the mechanism even if you don't knock them in yourself - see Dave's Volvo Page's article on odometer gear replacement for a good case study on this happening. If you can see the tooth in question, you may be able to remove it with a pair of tweezers, otherwise get a can of compressed air and spray liberally.
If neither of these work then I'm not sure I'm afraid - you could try inspecting for cracked solder joints, and reflowing any that are suspect (typical culprits are the ones underneath the black chip but any could be faulty at this age). Suspect joints typically look as if they have a very fine dark ring which signifies either a cracked joint, or a very nearly cracked joint. This seems unlikely though as it usually manifests as 'completely dead' rather than 'signs of life' like what you're seeing. Also could try double checking the orientation of that small gear is correct (see 12:10), perhaps it's meshing but not once it's got some force on it?
The fact it does twitch at least is promising though :)
@@unintegratedcircuit1073 Thank you for your time, effort, expertise and generous response. All is appreciated.
David - I have the same issue after changing the gears, with the speedometer working but the odometer rotor just twitching and not spinning. Have you found any solution? I am thinking that the UAF2115 chip may have failed?
@@user-ky5pv7nu5o I have no answer yet regarding the problem and solution. I actually repaired two odometers at the same time. One worked flawlessly and the other one twitches as described. The Arduino is a great way to test the function of a repaired speedo. My plan B is to send the speedo unit off to have it repaired. I see on eBay that there are businesses who say they will diagnose and repair a Volvo 240 speedo for $168. Considering the time and frustration that I’ve already invested, this looks like a good option. If there were some kind of schematic available, I might be tempted to try further diagnosis with a multimeter. I’m also open to any suggestions. As far as the UAF2115, I understand that it’s non-existent. 😩
Just had another thought, and a quick look at the datasheet for the chip; my findings:
The UAF2115 does indeed have separate output drivers for the galvanometer (speedo needle) and a stepper motor (odometer gears). [Figure 1]
The UAF2115 trigger input high voltage is specced to be up to 5V [Table 4.3]. Theoretically then, if your Arduino is only putting out 4.8V when high, plus some losses in the wire/PCB trace, and the chip is right near the high-end of that spec (or possibly even outside of it at this age), it might be not quite 'seeing' the pulse? I can provide a circuit diagram for a 5V -> 12V converter but it will require extra components and setup... Depends how far you want to run with it really
Datasheet link:
www.darisus.de/Elektonikshop/Datenblaetter/ITT/UAF2115.pdf
P.S. If there is demand, I would consider trying to build a tiny PCB to emulate the UAF2115, assuming someone hasn't done so already. I'm sure it could be doable.