Ignition or engine wiring diagram 93 S series

[S.Draizer]

I have a 93 SW2 that will not start. The engine has no sign of spark. I pulled the coils off and checked the primaries on both. They both read about .4 Ohm. I'm thinking they must be bad or somehow I am not checking it right. I checked the black wire with the white stripe on the 5 pin connector for the coil pack for resistance between the connector and the - terminal on the battery. It came out less than one Ohm. The Haynes manual I have says it should be 900 ohms (or something like that). I think it's strange that both coils would burn out at the same time and I am thinking that if there is an issue with the black/white striped wire it could burn out the new coils. I've been searching for an engine wiring diagram so I can figure out why there should be 900 Ohms resistance on that wire or if the manual is just dumb. If anyone can give me some info or advice I'd really appreciate it. Thanks.

[billr]

It cranks but won't fire, and no spark? Do you have injector pulses? No spark + no injector pulses would be a huge hint that the crankshaft position sensor circuit is bad. I assume you have checked the fuses...

[fdryer]

S.Draizer, '91-'95 is the older OBD I system. If the service engine soon light isn't blown (it should turn on then off at ignition on time) it may or may not be an ignition system issue. To add to billr's troubleshooting suggestions, one way to know if injectors are operating would be removing spark plugs for examination after repeated starting attempts - they should be wet and smell of fuel. Injectors operating indicates the crank sensor and pcm are working. No fuel on plugs suggests failure in one of several things; intermittent or dead fuel pump, clogged fuel filter, blown injector fuse, faulty crank sensor.

Check spark plugs for fuel and go on from there.

[OldNuc]

Originally Posted by S.Draizer

I have a 93 SW2 that will not start. The engine has no sign of spark. I pulled the coils off and checked the primaries on both. They both read about .4 Ohm. I'm thinking they must be bad or somehow I am not checking it right. I checked the black wire with the white stripe on the 5 pin connector for the coil pack for resistance between the connector and the - terminal on the battery. It came out less than one Ohm. The Haynes manual I have says it should be 900 ohms (or something like that). I think it's strange that both coils would burn out at the same time and I am thinking that if there is an issue with the black/white striped wire it could burn out the new coils. I've been searching for an engine wiring diagram so I can figure out why there should be 900 Ohms resistance on that wire or if the manual is just dumb. If anyone can give me some info or advice I'd really appreciate it. Thanks.

The HAYNES manual is a poor reference. That 900 ohms is supposed to be measured between the 2 pins that connect to the Crank Position Sensor, CKP. Go to my photo gallery and sort it by POST DATE ascending order and 90 per page. Then look for the DIS -1 through DIS-4 descriptions which will show which of the 2 connectors has the CKP connected and check it again. The usual failure that causes this with the early cars is either a failed ICM module OR a loss of the 6X signal because the connectors are shot.

Another point. The system is critically sensitive to low voltage and IF the battery is not fully charged the voltage will drop low enough that the ignition will fail while cranking. Full charged is 12.6 or above before hitting the key. Your coil reading on the primary is likely correct and the secondary is 7k ohm or above, that its the terminals where the plug wires connect.

No 6X there will be no injector pulse while cranking.

[S.Draizer]

Thank you everyone. The fuel pump turns on with the key in the run position and there is fuel on the plugs when the engine has been cranked. Fuel sprayed out of the schrader valve on the fuel rail when I stuck a screwdriver in there. It seems that Haynes strikes again. I tested the primary on a new coil at the parts store and it had the same .4 Ohm that my coils have (Haynes says 900 0hms for the primary!). The crankshaft position sensor seems fine, I'm getting the correct resistance checking it from the ICM 5 pin plug. I'm thinking it must be the ICM not working. I should be able to pick up a new one at the parts store soon. Thanks for the ignition wiring scheme OldNuc. Puts my mind at ease about the black wire with the white stripe (ground) that Hanes says should have a resistance of hundreds of Ohms. I think I need to burn that Haynes manual.

[OldNuc]

Haynes has been determined to be edge bound toilet paper at best.

Beware that an aftermarket ICM can be defective out of the box. The general recommend practice is to see if you can find a 93-95 ICM at a pick and pull and the 91-92 will also work fine if you can find one. Other than that it is aftermarket, avoid AIRTEX WELLS. It is the coil secondary that should be checked for the correct resistance.

[S.Draizer]

Just want to say thanks again to everyone and that it was the ICM. I picked one up at Auto Zone and the car started right up after I installed it. @OldNuc I don't know what brand ICM it is. I might have to check. Also, want to thank the Hanus repair manual for all its "help".