Hello, I have a problem in R129 1999 6.0 with the ADS light that flashes after starting the engine. The light goes out after a few starts and sometimes does not come on at all. When the light flashes, the car moves down. When the light flashes and I touch the return line to the tank, I feel a cyclical impact on it.

 

Sounds like you need to swap out the capacitors in the ADS II controller.

It would also be helpful if you took the car to a mechanic to scan the ADS system for diagnostics. This scan is of course different than an OBD scan.

 

Hi,
the light flashes, because the car moves down, not the other way around. Is the oil level in the reservoir OK? Is the oil foamy? Is the suspension very hard? There a connecting rod on the control module at the front and on the rear axle, are the joints intact and free of play?

 

If the car's ADS is in the toggled down position, the lights shouldn't flash at all.

Unless something is wrong.

 

That's what i tried to say: Something is wrong > car moves down > light flashes. Or something complete different

 

Describe the problem again, kinda hard to understand what your describing

 

The problem was that the car fell down, but not every time the car was started. If you managed to start the car without the light flashing, everything was fine. The problem was the ADS control unit capacitors

 

Did you use my thread?

 

No, the control unit was already removed before, but your thread only made me more sure

 

My experience with the ADS II system was cleared by replacing the capacitors.I also found that these capacitors can be tested in circuit. You will get the same reading installed as you get with the caps removed, so you can do a quick non destructive test before you pull them out. I also found that FAILED CAPACITORS WILL NOT SET A CODE. So if your scratching your head test them.

I will add to this that replacing the caps can be intimidating. @mahunt advised me of these when I had the problem but I waited until I got all codes clear before proceeding. The board in the ADS module is coated what is called a conformal coating for keeping out moisture and minimizing corrosion. I went to the allaboutcircuits.com forum to ask for advice on this coating. It was suggested to use IPA to remove it, but that did nothing. So I believe it is a higher temperature silicone based coating. With the conformal coating in place you cannot heat up the capacitor leads to melt the solder. It acts like a ceramic coating.

So what I did was just scraped off the top of the protruding wire with a razor blade to expose some bare metal. Once you have bare metal, a well tinned soldering iron with a small chisel tip, pressing down on the leads will melt the solder and push the leads flush with the board. Once they are flush you can take the corner of the chisel tip to push them slightly below surface. At that point you can use a solder sucker to suck up as much solder as possible. More than likely the caps will still be stuck, but with a small pointed, well tinned tip on the soldering iron you can push them through.

With the caps now out clean up the holes as best you can with a solder sucker then pass a small ~1.5mm or 1/16" drill bit through the holes using your fingers only to twist the bit. Also clean the solder pad faces using a ~3mm, ~1/8" drill by hand. The holes on one side of the caps are smaller, I believe I had to use a 1.2mm drill bit on those. Be very careful using the solder sucker not to transfer any heat to the tiny and very close, surface mounted components. Now you are ready to solder in the new ones. You can re-apply conformal coating to the caps and soldered area. I believe this is a silicone coating.

I used went with the Vishay MAL213836221E3 because its size and temperature specification match the original. These are available everywhere and Vishay is the standard of the Aerospace industry.

https://www.digikey.com/en/products/detail/mg-chemicals/422C-55MLCA/11617902