Hopefully they looked carefully at and cleaned the TOS connector and the wiring there. Actually, check every bit of wiring you can get a look at. Could be a wiring harness problem. Did the dealer check the circuit from the correct ECU pin to the TPS? Still, if it is so sporadic, would be difficult t...

What can cause such a sporadic problem? I don't trust the car at all. Oxide build up on the connectors. Clean the connectors on the TPS and the ECU with electrical contact cleaner or MAF sensor cleaner. Corrosion under the wiring insulation. Inspect the ends of the wires, look for corrosion that ma...

redbeak1 wrote: ↑09 Aug 2019, 20:41 Can anyone tell me which ECU pin I should test along with the TPS connector.

ECU pins A15, A16 & A18.
A15 TPS Out
A16 TPS IN
A18 Ground

Check Junction 23/8.

The Electrical Wiring Diagram for the '96 850 is document TP3911202.

7/54 is the TPS.

Did they checked TCU for fault codes? Erikv11 have good point about this. TCM,unlike ECU and ABS control unit will not clear the fault codes itself when parts are being replaced. They will remain stored untill read and cleared even if parts is replaced...AND will not proceed further untill codes are...

... replace with the new improved Knock sensor without the connectors at the sensor. I now find out that I have to splice it into the wiring harness. IPD has no instructions, and all I can find is that some people have connected it with a kit from Volvo. Does anyone know where I can find instructio...

Loosen the mounting bolts on the starter one by one, remove, clean threads shiny with a Dremel, lubricate, reinstall, torque to specs. Remove the back mount on the starter, to right side of car, if you have one. Volvo discarded it later on as unnecessary. Torque spec for starter bolts is........40Nm...

Okay, I'm back to say that my entire attempt to fix this problem has been a HUGE red herring. I can say that I have now fixed the problem and it has been over a month , and the problem appears to be gone for good. Here is what happened: So, as I posted earlier in the thread, I thought that the issue...