C70 2000 ECM/TCM

[speedlimit6869]

Hello everyone, at first start up - eveything is fine, while driving along my traction light my be on or will come on, and at anytime my winter mode light will start flashing and try to go into winter mode, my red brake light may-and will-come on,(no not the park brake light) now once all three light have come on in only a 10-20min. drive my speedometer will not work (it falls to zero) and my miles display will go to ----- that. I have been slowly trying to pinpoint the problem before I buy any major parts, or give it to a electrical shop. during to past cold spell we had at 14 degrees, the car performed flawless, the cruse control even worked when I thought it didn't at all, I press the winter button and it didn't blink, the car acted very normal. which leads me to belive that the TCM/ECM act crazy when they get hot... first off which one is the ECM and which one is the TCM. Is there any troubleshooting steps I can use also.

[RigsPGT]

I bought my 99 with ETM (electronic throttle module) issue and even though I kinda knew the culprit, after purchasing Vida Dice, I found out a ton of codes which the regular OBD2 scanner couldn't see. I would strongly suggest you to get it or find someone close by who can scan the car and go from there. For the price of a trip to Volvo ($100-150) you can have Vida Dice in your toolbox and use it anytime you feel like checking the car for faults.
If you're not into DIY, find a Independent Volvo shop as they have Vida and have them scan for faults.
I've heard the display can go bad and I once had it happen but after removing the negative battery cable and connecting back, the display came back to life.

[abscate]

You probably have a ABS module failure which will take all these things out, but reading codes is the first step.

See my signature below for more guidance.

[speedlimit6869]

I have a verdict snap-on scan-tool which cost me $6,000 new with the euro pack for my wife's Mercedes, and I do most of all the work on my cars. My ABS light stays on when the key is turned on but I figured that to be secondary and would fix that after the trans shifting and engine stumbling problem. I bought the car like this and found out that it was in an accident before. The dashboard works properly, no false alarms there. The scan tool shows the same thing the dash displays but it's not showing what components are bad or not working. I can clear out the codes but they come back.

[scot850]

I just bought a 2000 V70 base with a flashing trans arrow and engine check light on. I got no comms with the TCU so took it to the dealer to see what they could find. They had the same comms issue (I have a copy Vida/Dice system). Due to his knowledge the mechanic removed the TCU and ECU and found oxidation on the pins. They have a Wurth contact cleaner product that the apply with a cotton bud. He then installed and removed the TCU and ECU a couple of times, checked the codes (now had comms from the TCU) also threw up several ABS codes (no ABS light on). He cleared all the codes and nothing came back on on the way home (about 25km). Cost including diagnostic was $170 CDN (about $140 US).

Neil.

[Matty Moo]

If your trans is going Into limp mode (flashing arrow and 3rd gear starts) when the speedometer drops out then that's the fault of the abs module. Rough running isn't associated though

The scanner should be pulling the abs and obd codes.

[speedlimit6869]

I never pulled the modules out to check the pins and I never pulled the ABS codes. I'll try those steps first and see. and I'm looking into vida dice software since we love and keep around Volvos. I'll update with my findings, thanks.

[abscate]

On your model the vehicle speed sensor us processed " through" the ABS module so when it goes, all Hades breaks loose.

I'll heartily recommend Matty's service as he opens and closes the units much more professionally than most of us

[speedlimit6869]

Abscate thanks. I did buy a new sensor but didn't install it yet - thinking it was something else.