Big ground problem

[dahicori]

Hello everybody! Long time no see...I dont have much time this year. I will not be able to tackle the oil leak before next summertime.

Well, there is another glitch. My bad (I cant only blame wheather)

I had to lower the right window. Then I could not move it back up. I went back home to think about a solution, then I forgot , and it started raining cats and dogs . When I realized it was too late. I kept the window mechanism from my old 740 (RIP), and fortunatly, the button was the culprit. But I had to drain the water. At first, the temperature gauge went crazy, but went back to normal in no time. But I am still encountering strange electrical issues. When I push hazard button, it makes the belt signal flickering. Sometime turn signals works, sometime not. Most crazy thing that happened yesterday : when I move slightly the stick, it activates brake light!!

I definitly have a big ground problem. If anybody have any alternative to the complete removing of the harness, I would be glad to hear it

[v8volvo]

I think you are right that a ground problem is the most likely cause for the behavior you are seeing. Maybe got a corroded connection from the moisture in the interior, or it could be unrelated and just old or loosened up. Either way, same process.

Not having much familiarity with the 200 series electrical system, unfortunately can't say where you would want to look first. Perhaps someone with more 240 knowledge will be able to chime in. But the Volvo greenbooks I have for the 7 series do have a section about grounds that shows all the ground point locations around the entire car. Maybe would be good to find a 240 greenbook for electrical system and look for the same thing?

Other than that, if I had to guess where the ground locations would be, I would start by looking under the dash around the firewall and the kick panels on both sides. Seems like that is a common area for harness grounds either way. Maybe the transmission tunnel console/handbrake area also.

[dahicori]

thanks for your answer V8. Here is the main issue : I do have the electrical schemas in my book but I feel clueless...i dont understand a thing. I am looking for a straightforward method : if I understand, I have to check every ground to check the value and then identify a bad one ?

[v8volvo]

Originally Posted by dahicori

thanks for your answer V8. Here is the main issue : I do have the electrical schemas in my book but I feel clueless...i dont understand a thing. I am looking for a straightforward method : if I understand, I have to check every ground to check the value and then identify a bad one ?

You don't have to be that rigorous.

Checking resistance to ground (or voltage drop on a circuit with electrical load, which is a more useful measurement for the kind of issue you're looking for) would be the technically correct diagnosis method. However, you could also just refresh all the ground points (disassemble, clean, tightly reassemble), which would be much easier and faster, and would probably solve the problem. There aren't that many ground connections total so this would probably not be that time-consuming. It's one of the few cases where trial and error is probably the best option, rather than pinpointed diagnosis.

If you wanted to be a little bit targeted, one way to do it would be to use your electrical diagrams to figure out the specific ground locations that are identified as being involved with the circuits where you have been noticing problems. You could start by going after those, and see if cleaning and tightening just those grounds helps, rather than taking a shotgun approach and doing them all.

[dahicori]

You're right. Sometimes, overthinking is a real pain in the ass . At the beginning of summer, my overdrive stoped working. I spent countless hours on the web trying to figure out what the hell is a solenoid, how the mecanism really works. I looked for leaks....until out of curiosity, I looked under the stick : the blue wire was cut off. And i rode like 600KM without overdrive!!!


I will do that this week end, along the rust treatment.

Just another question : does it worth it to change the oil of front and rear axle? I know rear axle has less than 50 000km. But it stagnated in the car for 10 years

thanks!

[ngoma]

Rear axle oil: I would follow the factory maintenance interval. Rear axle and differential are not subject to all the harsh conditions present in the engine where there are mileage and time intervals. The engine oil suffers additional harsh conditions such as high temperatures, fuel dilution, and potential acidic conditions from combustion byproducts and condensation.

Front axle oil: There is none. Don't overthink it!