1994 850 No start, no spark

[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.

???????????

[jblackburn]

The only other suggestion I have would be to start probing the voltages at the pins at the ECU themselves. I attached this, but you already have it if you have the service manual from the site.

pin voltage charts.pdf

(51.98 KiB) Downloaded 280 times

In particular, you'll want to check the grounds at A20 and A29, the control signal to the main relay,and the POWER STAGE (ignition coil) control signal from B13. That's the one I suspect - I would check these wires for continuity from the ECU to the coil.

B13 - Power Stage Control Signal (Ignition On) 0.15 V
Power Stage Control Signal (Engine Idling) 0.6 V

That said, if everything checks out OK, continuity & voltage-wise, I'd bite the bullet and replace the whole thing. Someone above mentioned they had a replacement they'd be willing to send you.

[1994_850_owner]

Thanks to jpgurley I am now the proud owner of three ECUs with the same part numbers and version numbers.

I put in the ICU and checked it and it came up 111. I prayed and gave it a whirl and it did NOT start. I checked A6 and I got error 314 again.

I cleared the code and put in the EFI/Engine ECU and the TCU. What the heck I had all three as a set and they all played together before. All codes were also 111. I tried to start it and to NO avail. A6 still shows 314.

I am now going to try and see if there is any voltage at the ICU pins and then ohm them out to the CPS and ground. I know that this is going to be tough to do without a breakout box, but I don't know what else to try at this point...

Does anyone have any ideas of what the three overload relays do- the ones with the "J" on them??? Someone mentioned in another post that he replaced one when he had similar problems and everything worked. He did not remember which one though....

Thanks again for all of you all's help and advice. I guess that I will keep plugging at this...

Don

[1994_850_owner]

OK. I went out and checked the wires as jablackburn suggested.
_______________________________________________________
In particular, you'll want to check the grounds at A20 and A29, the control signal to the main relay,and the POWER STAGE (ignition coil) control signal from B13. That's the one I suspect - I would check these wires for continuity from the ECU to the coil.

B13 - Power Stage Control Signal (Ignition On) 0.15 V
_______________________________________________________

I checked for voltage at B13 with the ignition key on and I received 0 volts. I don't know if this was because I had the ICU unplugged and I was checking at the connector.

I checked for continuity from B13 to the power stage unit and it was OK,

I checked A20 and 29 and there was 0 ohms to ground, and 0 ohms between both of them.

For the overload relay shown on the wiring diagram I checked for voltage at both sides of fuses 1, 2, 8, and 33- all OK.

The other two relays don't show up on the diagram so I don't know which one I was really checking out of the three.

I also ohm'd out all three wires going to the CPS and the ICU and they ball checked out OK too.

I will go to the junkyard tomorrow and check the CPS and try to get an OEM. While I'm there I will also grab the "J" overload relays as well as the fuel pump relay. Maybe even the Crankshaft positioning sensor because I replaced mine with one from Auto Zone- Duralast.

Anything else I should look for and try to get??

Thanks again for all of you all's help and advice. I guess that I will keep plugging at this...I've got a lot of time and money invested in this to give up now. It's only a machine right, and we are smarter than they are, right.......

Don

[jblackburn]

I checked for voltage at B13 with the ignition key on and I received 0 volts. I don't know if this was because I had the ICU unplugged and I was checking at the connector.

There should still be a voltage signal fed through that wire. I don't understand either. I wonder why it's refusing to output a voltage to B13. I would have thought a new computer would have fixed that.

I have no idea what the overload relays do, but if you can get your hands on them, hey, it's worth a shot. I would THINK it would shut down more than just the ignition coil though, but I could be wrong.

Get your hands on a Bosch cam position & crank position sensor from the junkyard as well. These cars are very picky about their aftermarket parts.

It's only a machine right, and we are smarter than they are, right

Haven't you seen I Am Robot? Or Terminator?