Thank you for viewing this post. Having driven and repaired Volvos exclusively since 1978 I'm reached a point w/ my current ride where I know the problem - No Spark - but I can't figure out what is causing (or preventing) my ignition system to spark from the coil/primary wire. This post is kinda long but in order to obtain advice the more information the better the advice and wow, do I need advice!!


The CAR:
1994 850na, manual trans, 250K+ miles wagon, I’m second owner, always serviced from new
it was running fine, no intermittants, good mileage, etc. Good, good, good.

I also own a 93 850 that runs, (important as it became a “swap parts” car) except for a bad water pump. This 850 was starting and running on the day problem arose.

I was setting up to replace the water pump on the 93 Volvo 850 (the one that starts and runs) when:my Wife backed out of her garage and bumped the front end of the 94 wagon. No big deal as there was no minor scrapes but not even a cracked grill.

Is there an electrical or other coonection near front grill that could have been cut, crimped or otherwise broken?

But now the 94’ 850 wagon won’t start. It apparantly has No Spark. To test this I replaced the primary coil lead w/ a spark plug and wire to ground. I also tried grounding the primary coil w/ just a speaker wire #14 but in each case - No Spark. I’ve repeated this test each time as “repairs” were made but -no spark!

I also went over the No Gas Problem before determining it was a No Spark Problem; Schrader valve, fuel pump relay , etc Fuel is fine

From the A6 receptacle on the OBD I’m reading two fault codes: 314 and 214. The 314 is “314 “Camshaft Position sensor (CMP) signal missing or faulty” and
the 214 is “214 Engine speed (RPM) sensor signal missing sporadically“ I now also get a 121; “121 MAF sensor signal” from A2 but when I first started this 121 fault was not indicated. Apparently I subsequently damaged the MAF while working on other problems. I have tested w/the MAF disconnected, and I have tested w/ the MAF connected but still no spark. I am under the belief that with the MAF disconnected I can still start the engine. At least get a spark. Pls advise if true or not.

So NO Spark, CPS fault and after reading this blog I also assumed the 214 was related to the crank sensor. So I replaced both the CPS and crank sensors and the primary coil in the non-starting 850 with the same parts from the starting 850. Still no spark. I cracked the Bakelite connector on the CPS while swapping so I went to the bone yard and got additional CPS, crank sensors and coils. Still no spark. I’ve swapped in two sets of CPS, crank sensor and coils one from a known working motor. BTW the parts from the boneyard were from a car w/ deployed airbags so I assume it was running up to point of collision

BTW: I’m jumping the battery from running car so the volts/amps are good. +13.5 at battery

W/ a VOM, w/ jumper cables & running car attached, I read:
Battery terminals: +13.57
at the CPS connector: +12.5V, +5V and 0V
I am dropping 1volt from battery to here but a) its more than the required 11.5 and b.)it’s probably due to line risistance
At the crank sensor connector: 0v, +1.67v
at the COIL: +12.5 at both “nuts” , connector: 0, 13.5, 00.15v (transient)
MAF (what the heck): 0,13.5, 0, 0

I am lost...
The battery volt/amps are good.
CPS, Crank sensor & coil have been swapped out. Voltages good
Schrador valve emits gas. fuel pump relay (103) has been swapped, I can hear the fuel pump when I turn key to position II. Fuses etc checked and good. Little stuff done
And yes the IAC humms, buzzess quite happily when key in second position. swapped out primary coil wire (twice)

Yet still no spark!!!!!!

ECU bad??? I hesitate to think this as it is a difficult TS w/o risking my spare car. What’s the deal w/ the ECU’s? Are they interchangable between a 93 850na manual trans and a 94 850na manual trans. The “numbers” are different on the labels between my two 850’s.
ECU numbers (standing in front facing engine)
Non-starter:
Right ECU (nearest to engine in BIG #’s) 4.1;
also on label: PO9146296; CP01, 1T2250685; T94050203
Left ECU: 1.2
plus PO9146476; CP01; 1T2852395; T94020348
Can someone provide an explanantion of ECU’s and interchangeability. On my (previously) running 850 I have a (previously) good engine
rightmost ECU 3.1; P03517961; CP03; 1T2250646; T92462263
Left ECU 4.2; P03517962; CP03; 1T2852210; T92480274
Can these be swapped w/ broken 1994? If you’re not sure pls don’t guess I don’t have another

Anyhow I don’t know what to do next other than giving up and throwing in the towel. I have a signal tracer with which I can trace for continuity on the wire harnesses but I don’t have a complete wiring disgram that goes to the CPS, crank sensor, ECU pin-outs etc.

Can anyone point to link to ECU pinouts? I’d like to know if the CPS and crank sensors are connected to their respective ECU connections

I’d try swapping ECU’s but that can be an expensive rathole. And since I don’t know enough ECU’s are a potential landmine for me

It appears I may have been following the wrong supposed “problem” with my emphasis on CPS, crank sensor etc but I just don’t know what to do next. I may get a buddy to come by w/ a truck and drag the 850 trying to jumpstart it but wow for the first time in a long time I’m clueless.

so:
no spark, fuel ok, good battery source (cablejump), swapped out supposed “bad” parts; CPS, Crank sensor, Coil for known good, and coil wire - still no spark. HELP

Any suggestions from those on this forum will be appreciated and tried.

Paulfr