94 850na Won't start;No Spark;Can't locate fault;need advice

[paulfr]

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? 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

[misha]

... 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.Paulfr

One thing is for sure...Maf have nothing to do with a spark.

...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.Paulfr

Hmmm,there is ONE more thing to check:

It's a master fuel injection relay located at a fan shraud/cooling fan carrier.It's a grey one and it says VOLVO(Made in Hungary)on it.Here is the picture of it:

relay.jpg (65.52 KiB) Viewed 5005 times

Since your iac valve works along with a fuel pump,maybe it's not a relay.But maybe it is.

Nothing else was in the way when your wife bumped the front end except that relay.Check it out and also check connection wires FROM and TO it.

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“

Since you have pre-OBDII car(meaning...you have obdI)maybe your CPS & RPM sensors are indeed bad.I'm telling you this because OBDI is much,much more precise than OBDII,and it's leading you directly to the fault.

There is possibility that those sensors are bad(you mentioned that you presumed that they are working)...OR ...it 's because of a grey relay.

I assume that you ruled out immobiliser & that it's not a source of a problem.

[paulfr]

Misha, thanks for your response. I will swap out that relay for the one on my other (formerly running) 850.

That relay drives the fuel injectors however and I have a No Spark problem. I'll still replace it as I've seen screwy things prevent Volvos from starting.

I want to believe the OBD I signals but I'm confronted w/ the FACT that the CPS sensor has been replaced w/ a known, good replacement. Although "used" I took it off a car that had started not less than 60 minutes earlier. Same for coil and crank sensor.

Since I have to replace cannibalized parts for other 850 (83 sedan) now I can check again that the swapped parts are okay. If the 93 sedan starts will parts back in place I will know the OBD I signal is masking another problem. Correct...yes??

Thanks for your assistance..any other ideas appreciated.
Paulfr

[osman]

ECU's cam be swapped from other 850's however some of the 93-94's havs a different pin configuration than the 95-97's. Dont believe anyone that tells you they need to be programmed by the dealer because they dont.
ˆhave some 850 ECU's both the early and late. PM me if you need one

[osman]

And I didnt hear anything about ignition coil, distributor, rotor, wires plugs either. Those are obviously all no spark issues.

[Willhobby]

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? 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.

Did you ever figure out what the problem was ??

[abscate]

Old thread alert , user last active in 2013

[pkc303]

Would've have been nice to know the result. I have a very similar problem.

[abscate]

Usually people who don't post back found something silly or didn't want to follow the troubleshooting advice given, so you rarely get good feedback in these cases.

Take the plunge and post up your symptoms in a new thread, following the guidelines and title

1997 850R No start in TX

but check out the no-start thread up above first of course. You can skip the compression test if you had a good runner that suddenly cranks without starting. The folks here are great and non-judgmental, we don't care if you have never worked on cars before in your life - we just keep Volvos running.

Sometimes you might have another enthusiast nearby and you can make a friend and get your car fixed, too!

[pkc303]

Wilco