96 850 no spark. New cam, crank, coil

Senseill · Post by **Senseill** » 24 Apr 2018, 14:38

My 1996 Volvo 850 has no spark. Please help? I Replaced cam shaft sensor, crank shaft sensor and coil pack. I also cleaned the connectors with electrical spray. Also, checked the cam shaft sensor wire for continuity.

Post by **RickHaleParker** » 24 Apr 2018, 19:10

1996 was a crossover year for the 850. Lots of different configurations.

Which engine?
B5234FT, B5234FS, B5234F4
B5252FS
B5254FS

Which engine management system?
LH-jetronic 3.2 & EZ 129 K, Fenix 5.2, Motronic 4.3 or Motronic 4.4

Post by **erikv11** » 24 Apr 2018, 20:26

A 1996 US model will be either Motronic 4.3. or 4.4, those were the only systems. Turbo or non-turbo is likely irrelevant but definitely doesn't hurt to know. Use this link, and your VIN, to get the details: http://new.volvocars.com/ownersdocs/199 ... n1996.html

That said, hopefully none of that matters (e.g. unless the problem is the ECU, and it's never the ECU).

Just to make sure you exhausted the simple things: consider a bad wire from the coil to the distributor cap, or a bad rotor inside the cap. Did you check the coil wire for spark, or just the plug wires? Not clear to me from your post. If there is spark from the coil I would also pull the cap to make sure it is not broken inside or hiding an oily, wet mess inside there (blown rear cam seals).

How old are the wires (including the coil wire)? There will be a date code on them unless they are junky aftermarket stuff, in which case you will want to replace them. But bad plug wires won't explain zero spark, if the coil wire is intact.

How are the engine grounds?

Senseill · Post by **Senseill** » 25 Apr 2018, 10:11

My engine is the montronic 4.3. I’m about to leave for work. The distributor cap, spark plugs, and rotor are less than 2 years old. No moisture in the distributor cap. The inside of the cap turns. No cracks in the distributor cap. I’m not a car expert. I watch YouTube to figure out how my vehicle works and how to fix it. Chauncey tested the spark plug and they don’t spark. He used a screwdriver to test the spark for the coil and the old coil didn’t give spark but the plug connected to the coil was getting power. I hope this gives you more insight. I did order a used ecu off eBay just in case.

Senseill · Post by **Senseill** » 25 Apr 2018, 10:13

Also, my engine is a non turbo. I see 2 ground wires one on the engine and one by the coil pack. That ground wire goes back into the wiring harness. They are not rusted but dirty and are tightly fastened to the vehicle.

Post by **RickHaleParker** » 25 Apr 2018, 18:03

coil didn’t give spark but the plug connected to the coil was getting power.

Power alone is not enough. The wires need to be checked to see if there is a pulse when cranking. The coil is discharged by interrupting the power. That is the ground on the input is disconnected to fire the coil. Reconnected to charge it back up.

A computer safe automotive logic probe is the tool to use. The older incandescent bulb test lights can overload and burn out electronics.

1996 Volvo 850 wiring diagrams.

callahanoffroad · Post by **callahanoffroad** » 25 Apr 2018, 18:56

This will sound silly, but did the fuse blow?

I had my fuel pump fuse blow back in october, and I thought I had a bad fuel pump. Turned out to be a $3 fuse instead of a $250 fuel pump.

Post by **erikv11** » 25 Apr 2018, 22:01

Good news about the visible condition of the distributor cap. Ground wires may be fine too. There is another one near the battery.

What brand is the rotor that is less than 2 years old? You may be zeroing in on it as a suspect. The rotor has electronics inside that can fry, so the rotor may look great but be non-functional. Happens more often with aftermarket rotors, rarely if ever with a Bosch rotor. A junkyard rotor is one way to test. Or ask someone on here to send you one if you have a few days to wait, I have several spares ... These cars really shouldn't be run with anything other than a Bosch cap and rotor. If the recent rotor is Bosch that would disfavor it as the problem but still a possibility without a test. Not sure if you can test continuity through the rotor with a voltmeter (testing for resistance), but you should be able to.

Senseill · Post by **Senseill** » 26 Apr 2018, 11:55

I’m going to go buy a logic probe. The fuse is not blown. That’s the first thing I checked. Also, I believe it’s an after market rotor and cap. I can buy a Bosch rotor for 18 dollars on rockauto.com. Since I ordered a used ecu on eBay I want to make sure I got the right one. I know the numbers need to match up. The closet one I could find had all the numbers match except 1. The bottom right barcode number doesn’t match. Is that going to matter?

Post by **erikv11** » 26 Apr 2018, 13:10

Good move on the logic probe too. Would be good be certain about the coil and spark before you spend on a rotor unless you want to make the ignition parts Bosch anyway.

The problem is not the ECU, it's never the ECU ... well almost never.

Any ECU from a USA spec 96 850 NA automatic will run the car just fine, doesn't matter if it is 4.3 or 4.4. If you want to try to match the ECU, use the 10 digits right under the Bosch logo, on the top left corner of the ECU. Still, it may be flashed for different emissions than your car has (e.g. air pump vs no air pump), so you could see a CEL and error code when it starts. The only way to be sure of that is to either know the VIN of the car it came from, or see the car it came from, etc.

Once you have it running I would get a Bosch distributor cap too.