1995 850 No start, No spark

dtmmoore2 · Post by **dtmmoore2** » 27 Aug 2020, 23:22

My 1995 Turbo standard drive 850 was parked for a week and then wouldn't start. For some reason the onboard diagnostic unit on output socket No. 2 does not provide any DTC's (first time I run into this situation; Socket No. 3 and No.7 do display DTC's). I checked for spark and there is none. I removed the distributor cap to look for possible crack (its been raining a lot lately and I had been experiencing a lot of misfires that would resolve in drier conditions) and found no evidence of short. I had a look at the layout of the fuses and noted only one related to ignition system, a 15A in slot No.1 for the ECU. Visually it seemed not to have blown although I should have tried replacing it with one of the spares just in case. I swapped out the coil but made no difference. I have never beforehand tried to track down a short circuit in the ignition system for this car that I have owned for nine years. I am willing to try to avoid an expensive time consuming repair at a garage and would appreciate any suggestions for where exactly to look for possible corroded, broken or loose wire that may be causing the short.

Also, just before conducting the spark test I lowered all the power windows which have always worked. For some reason after perfuming the test and finding no spark, none of the windows would close. None of the fuses that are listed on fuse cover lid seem to relate to the power windows. So two electric issues that I am not sure could be related. I would be grateful for any advice to help me resolve the issue as well. Thank you.

Post by **abscate** » 28 Aug 2020, 03:53

Are you checking for spark at the plugs or at the coil wire?

The ECU depends on the cam and crank position sensors to tell it when to fire, so check those connectors, pen them up, look for fraying and green corrosion , on both of them

dtmmoore2 · Post by **dtmmoore2** » 28 Aug 2020, 08:05

Thank you for your reply. I checked for spark at the plug as opposed to the coil. When I removed the distributor cap I checked the cam position sensor connector and cleaned off the small amount of green corrosion. Also found a small tear in one of the boots (see attached pics).

I will check the crank position sensor as well. Hopefully its accessible from above once I move the air box out of the way.

I would like to check all the fuses etc. relating to the ignition system and now the power windows but the attached diagram listing the various electrical components does not reference the power windows and as I said the only relevant fuse I could find is labelled Engine (Transmission) Control Unit.

In case this further info is useful I would add that when I checked the onboard diagnostic unit on socket No. 2 the LED did turn on when I pressed the button but no DTC’s were detected which is odd because it’s been throwing certain codes for a long time like for example 514 (Engine Cooling fan low speed signal) and now coinciding with this no start,

Any further assistance gratefully accepted. Unfortunately, I am stuck at a very remote campsite with lots if rain forecast for the weekend.

Post by **abscate** » 28 Aug 2020, 08:55

All that green has to go, it might be bad enough that you need new parts and splicing in a new connector into the loom.

dtmmoore2 · Post by **dtmmoore2** » 28 Aug 2020, 10:44

Thanks the corrosion cleaned up nicely with a toothbrush and some vinegar. I am just about to get to the crank sensor connection. I guess maybe you were suggesting I should check for spark at both the plug which I’ve done (no spark there) but also at the coil wire to maybe narrow things down a bit, but like I said I have really no experience in finding circuit breaks on this car and would be helpful to know what I should be checking for instance In terms of fuses etc. on top of everything I mentioned that I have checked (distributor cap but not the rotor .. should it be removed and checked?) or switched out already (i.e. the coil and the 15A ECU fuse) that might explain a no spark situation.

Good news is that I pulled the circuit breaker relating to the power window and plugged it back in and they all worked once again... the fuse cover did not refer to the power windows but thankfully the owner’s manual did. I wonder why it suddenly became necessary to pull out this CB immediately following the spark test yesterday. I hope it is not going to be a recurring issue.

Thanks again for your help.

Post by **abscate** » 28 Aug 2020, 12:08

You’ve got no spark at the plug.

You work backwards in order, not skipping around.

Pull the center coil wire at the distributor and do a spark check there.

A wooden clothes pin is great for holding the coil wire

You can also pull a spark plug and wire and plug into the coil ( I think the connectors are the same )

dtmmoore2 · Post by **dtmmoore2** » 30 Aug 2020, 12:26

Hi thanks for your reply. Similar to the cam sensor connector, I had a bit of corrosion on the crank sensor connector that cleaned off with vinegar (see pic). I have now checked and I have no spark at the coil (I pulled the center coil wire as you suggested). I then swapped out the coil once again (I mentioned in my first post that I had tried it with no luck) just in case. Someone who is encouraging me to fix this on my own suggested that the chances of the two coils I have being dead were slim. To be clear, I am swapping with a used one that I picked up at a scrapyard as opposed to a brand new one. Prior to this I had shined up the rotor contact and all the contacts in the cap.

As a contingency, I have ordered new cap, rotor, wires and coil. I am assuming that the two position sensors are not an issue at least until I recover spark at the coil.

I have attached pics of the Motronic 4.3 ignition testing process. It confirms at paragraph No. 11 the test involving the coil wire which my car has failed and indicates a new coil is required.

On the other hand, I am confused and curious about what is stated at paragraph No. 5 which refers to the ignition coil four pin connector. I am confused because it refers to the No. 4 fuse which should be replaced as necessary. However, I have been relying on the attached diagram of the fuses, relays etc. in addition to the fuse box lid for this car. The lid shows that fuse slot No. 4 is supposed to be empty. So how is this fact squared with what is stated at paragraph 5?

Any clarification would be appreciated.

I have included some pics to give an idea of the condition of the electrical contact in play.