My new pain - 2000 project V70 and random dash lights Topic is solved

[scot850]

Been corresponding with that marvelous guy Matty Moo. I have bought from him before, and he is always a font of knowledge.

I got the impression from him that he was dubious that the issue was ABS module related. He may well be correct on that, but I'm not convinced the issue is resolved yet.

I spent a fruitless afternoon working on trying to extinguish the bulb failure light, only to discover that it is not the bulb failure light after all. Apparently in Canada, we have to have 2 symbols on the warning lights that look very similar, but one is orange (bulb out light) and one is red (brake fault light). What was on was the brake warning light along with the ABS warning light beside it and occasionally the STC light would come on and an engine check light.

The engine check light finally threw a code, P0600 comms error. No idea what that is or why. One of these purposely useless codes that are set to drive you mad.

Strange thing is I went threw all the bulbs and found one of the rear license plate bulb badly corroded and a back-up light bulb out. Replaced those and cleaned the contacts. That was when I discovered I was chasing the wrong issue.

Checked the brake fluid, removed the header fluid cap, and re-fitted it after seeing the 'clean' fluid was ok for level. Tried to remove the ABS module connector but need to have another look at PnP as to how it comes off as I don't want to brake mine. Strangely did remove one at PnP on Saturday and it came off with no problems.

Tried locking/unlocking the drivers door lock in case it e comms issue was just the immobiliser needing reset. Reset the engine check light with my basic tester and started the car. Now all lights are off again? What the heck??!

No idea what I did to delete the warnings, but even the milometer and trip are back on. This car is typically weird of the breed and set in this world to drive me mad(der!).

Not convinced I have seen the end of this issue yet, so will wait the random returns and try again.

May yet be bad connections in ABS module or wiring connector. But who knows?!

Just looked up the P0600 code under Volvo P0600 code, and the link below is actually spot on. The descriptions are exactly what I said, so apologies to the P0600 code and its warnings. Best to read the link info as it does a better job of explaining the issues than me.

https://repairpal.com/OBD-II-Code-P0600

Neil.

[scot850]

Well, they are back. Add to that the speedo also died for a short time. However, the one difference was the brake/ABS/STC lights all came on together and then the first 2 went off and the STC stayed on. At the same time these came on the Milometer/Trip/speedo all died while driving. Then all went off about the same time and the speedo/milometer and trip all came back on leaving just the STC light on.

So question is, what can affect all these system/warning lights? These were not on when bought, so I have to believe it is something I have somehow introduce during the repair. Matty Moo's thoughts were that these (certainly the speedo/tip/milometer) are all the speedo unit issues and not the ABS. Could it be they are all speedo cluster issues? I had the cluster out twice to replace the illumination bulbs so maybe I could have disturbed something or possibly have a bad speedo unit connector?

Thanks,

Neil.

[Teddy1975]

... the dealer had to remove the ECU + TCU and clean the connections to get the system to talk...

It sounds more like some of those connections might still be acting up, Neil. I don't know for sure, but my guess is the warning lights in the cluster are only a visual representation fed by the ECUs. So the problem is possibly not in the cluster at all. Can you ask the dealer if they cleaned all of the connectors or only the ones for getting the OBDII to work?

[scot850]

Thanks Teddy, from what the mechanic told me at the time, he cleaned all the contacts. I have to believe it is an electrical snafu somewhere. Maybe it was there before but with the other stuff going on with the TCU is was masked?

First order is to remove the speedo again and have a good look at the speedo unit and the wiring connectors.

What I am trying to understand (electrical stuff is not a strength) is is there something that could affect all these items which would appear to be speed/distance related.

So, for example, what determines the speed and distance signals? Is it an ABS sensor, or something in the TCU? If it is an ABS wheel sensor that I damaged during repair for example, would that affect the brake issues and the speedo?

I don't understand what the interaction of the cars systems are to know where to look other than stab in the dark for a solution.

Neil.

[Teddy1975]

On the 850s the speed is determined from the front wheel ABS sensors, I'm not sure about the V70. It could be picking up a signal from the transmission too. More knowledgable people should chime in here.

However, if an ABS ring or sensor is damaged the ABS will disable (and the warning light will come on) after driving approximately 100 metres and the light will be reset when you power off the engine, only to come back the next time you drive.

[scot850]

Today when the lights came on it was after about 5km of driving. I had stopped to drop our daughter of at the station, and had driven about 100m to a set of lights and all the lights came on as I was either just approaching the lights at a slow speed to turn left. Then the lights all stayed on and speedo not working for maybe another 800-1000m and then all the lights went off except the STC light, and the speedo and milometer/trip came back on. To me it would seem clear that something electrical must be intermittent or a connector is loose.

I pulled the dash off again and removed the speedo unit to see if any of the connectors were loose or broken wires. Didn't find anything except that the PO had managed to break 2/3 of the glove box door wood trim mounts. How the frik do you manage that. It has to be up there with the cracked antenna ring in how in the name of heck do you even manage to do that?

Neil.

[precopster]

On a 1999 V70 I worked on recently it had speedo dropping out, ABS lights and Brake Failure Warning light as well as Transmission Up arrow. Diagnostics showed ABS pump, front left wheel sensor and communication faults with ABS. I can post up a screen capture from Vida to see if there are similarities.

That ABS unit should have STC written somewhere on it.

All were solved by an ABS module replacement supplied by Matty. I think these "bastard" years may still get speedo reading from front ABS rings unlike later cars.

[scot850]

Thanks for your wise input too Mike! That was what I was thinking along the lines of. If my tinkering today made no difference then off to Matty it is. Although the car is not a turbo, the circuit board still gets warm so bound to fail eventually after the mileage it has on it (about 270,000km).
The module is an STC version as discussed and verified with Matty on the weekend via e-mails.

Neil.

[precopster]

The faulty one I had was a Part # 9496942 non STC which I couldn't find in Vida or Tasca's database.
Mine was actually a 2000 model looking back on my records.

These ABS V70/S70 modules for 1999-2000 years are shared with S80s if that's of any help.

[scot850]

Mine is 9496946 STC/ABS module. There are no S80's in the PnP locally. I'd rather gt a known good one from Matty as I am totally fed up chasing ghosts on this car and finding endless broken stuff I have never seen before. I actually have one of the non-STC/TRACS versions sitting in the garage from a 99!

Appreciate your time Mike,

Neil.