1994 850 No start, no spark

[confused_al]

I'm not sure 124 code, or even 134 code would be the reason for no start. Could that be the TCM at fault?

[jblackburn]

I'm thinking the ECM isn't communicating to it (or the coil) and causing the TCM to flip out and throw a code. Just a theory though.

[jpgurley]

Hey, I have a used ECM from a 94 850 I just scrapped out. (Locked up engine)
I'll sell it cheep if you can help me identify the part number and it matches.
JPGurley

[confused_al]

Pull both (TCM and ECM) out and clean the connectors and then clear the codes, see what happens?

[1994_850_owner]

OK. I took out the mode switch and checked it. It is all ok. I checked the winter button and it turns on the arrow just like it is supposed to. The leads going back to the TCM all check out too. I also tried starting in each mode- all to no avail.

I took out all 3 ECUs and sprayed them down with electrical contact cleaner and put them all back in.

I cleared all of the codes and tried to start again. Still nothing.

The TCM codes did NOT come back, but the A6 "314" did come back again.

Any other ideas???

Thanks,
Don

[confused_al]

You said you replaced the Camshaft position sensor (CPS) right?
What brand did you buy?
Take a look at this write-up:
https://www.matthewsvolvosite.com/forums ... =1&t=24925

[1994_850_owner]

I pulled out all three ECUs and sprayed the connectors with contact cleaner and put them all back in.

I cleared all of the codes and now the only code I get is A6- 314 for the camshaft positioning sensor.

Any other ideas???

Thanks again, Don

[1994_850_owner]

I have tried two from Auto Zone made by Duralast.

[confused_al]

As long as ECM giving you 314, it wont let you start. So you have to go back to resolve that CPS issue.
These Volvo's are very picky on sensors, I never used anything else but OEM/Bosch components on my Volvo/M-B. I couldn't tell you this Duralast is the problem or not. However, the fact is the sensor is not working since you checked everything else.
I know its frustrating, Don, sorry cant be more helpful.
When Lee checks in, he might give you some ideas to try.

[1994_850_owner]

The CPS sensor ohms out ok, it is just that it is not getting a grounding signal from somewhere- more than likely the ICU.

I checked and pin 1 has 12 volts and pin 2 has 5 volts and pin 3 is 0 volts-ground. When I crank over the engine I was told that pin 2 should drop to 2.5 volts but it stays at 5 volts.

Is there anything else in the circuit that can cause that signal not to get passed???

I have the new coolant temperature sensor and thermostat but I haven't put them in as of yet.

???????????