1991 Super Coupe, no spark

UBHSTRY

Registered User
Well, having my first issue with this car. I lost spark. Started backfiring a bit, then died. Started once more, ran good, then dead as a door nail. Has a new crank sensor, and ignition control module, replaced twice just in case one was bad. Still no spark. I am thinking I need to replace the computer. Anyone here throw any ideas my way? I have several hours into trouble shooting this, and simply cant get it to spark now. Got 3500 care free miles on her, before this happened.

Thank you!
Larry
 
Well, I thought, or made an ~~~ out myself...LOL That the DIS and Ignition control module where one in the same. So, please if you can give me direction to troubleshoot the DIS I would be grateful.

I was going down the road, it quite. Then acted like it was 180 backfiring, then after about 10 minutes it started back up fine and got me home. Did the same thing one more time, but now no backfireing at all, just no spark.
 
By the looks of things, what I am calling the ignition module is the DIS. The flat control module on the top left side of the engine, plugs on both sides. If so, its been replaced with 2 seperate new ones, and still no go. Also have put in two new crank sensors, and no spark still.
 
This is the unit I am speaking off. The ignition module I thought you were referring to the IRCM. Sorry I sometimes get the GM and Ford vocab mixed up. What compound are you putting under it?

Have the spark plugs been pulled and looked at?
 

Attachments

  • SC_Ignition_Diag.jpg
    SC_Ignition_Diag.jpg
    54.9 KB · Views: 1,402
Last edited:
Yes plugs are fine. I have even put another coil pack on it with no luck. I can grab the coil pack with my hands, nothing, nadda, no sparky. Good fuel.

Yep, the DIS is what I have replaced, with two seperate new units.
 
I also have torn the harness down, and was checking for a broken wire by chance. But, it all looks good. I hate things like this:rolleyes:
 
The cam sensor is the only other unit on that wiring diagram that you haven't mentioned. Backfiring, no spark, could be the cam sensor. If it is shorted you are done. Disconnect it and try two or three starts. If it does start on one of those tries, you need to replace the sensor. Costs about 50 bucks here in Canucistan.
Alan
 
That has also been done. Disconnected the cam sensor and tried to get spark. Still, no spark out of the coil pack. I do think I have done all the normal troubleshooting for this type of problem, hence why I am here....LOL I am into something I think is out of the ordinary for this car.:eek:
 
Are any other items non-functioning? The ignition switch itself is another common point of failure. Even though the car tries to start, doesn't mean that all contacts within the switch are still contacting. If you take the column trim off, you should be able to check the switch. When they start failing, it's because the plastic and metal halves start separating.

I don't have the schematics with me to check, but it may be a possibility.
 
http://www.sccoa.com/forums/showthread.php?p=733885#post733885

All this info is from other Posts by Jenny. Mike8675309 Thanks MIKE!!

See how Battery Plus goes to #8 all the time?
Check that.

See how Battery Plus goes to #13 with ignition run or start?
Check That

If you find plus at #13, then check for Plus at #24.
If you have plus at #8 and then nothing at #13, bad ignition switch or wiring.
If you have plus at #8 and #13, but not at #24, bad IRCM (CCRM).

Note how Power through EEC Relay is then tapped to trigger other relays. If you are unfamiliar with a relay wiring diagram, the coiled looking thing is the pull or push coil in the relay. With 12v flowing through that it will pull the switch (noted by an arrow between two dots) closed.

EEC and LFC relays have a diode across them to handle relay coil kick back, a current created when the electric field collapses when power is removed.
 

Attachments

  • IRCMElecDiagram.gif
    IRCMElecDiagram.gif
    35.4 KB · Views: 1,524
http://www.sccoa.com/forums/showthread.php?p=733885#post733885

All this info is from other Posts by Jenny. Mike8675309 Thanks MIKE!!

See how Battery Plus goes to #8 all the time?
Check that.

See how Battery Plus goes to #13 with ignition run or start?
Check That

If you find plus at #13, then check for Plus at #24.
If you have plus at #8 and then nothing at #13, bad ignition switch or wiring.
If you have plus at #8 and #13, but not at #24, bad IRCM (CCRM).

Note how Power through EEC Relay is then tapped to trigger other relays. If you are unfamiliar with a relay wiring diagram, the coiled looking thing is the pull or push coil in the relay. With 12v flowing through that it will pull the switch (noted by an arrow between two dots) closed.

EEC and LFC relays have a diode across them to handle relay coil kick back, a current created when the electric field collapses when power is removed.

Thanks BOP, I can not however go to that link. But I am going to go thru what you described there.
 
Well, it seems clear that you are not getting any primary ignition pulses out of the DIS. My thinking would be that the next thing to do is to make sure the crank sensor pulses are reaching the DIS. I don't have the pinout handy, but I would figure out which wire is the crank trigger, then backprobe that pin in the connector and use an analog voltmeter to make sure 12V pulses show up when cranking.

And, of course, make sure that the DIS has power and ground in the first place. :)
 
Thanks BOP, I can not however go to that link. But I am going to go thru what you described there.

Try this.

Never hurts to pay the $15 for membership. If you havent done that yet I would strongly suggest it.

This pin out is from a 90. Seems there were a few changes somewhere between 90 and 93.
 

Attachments

  • IGN%20switch%20#2-1990-jpeg.jpg
    IGN%20switch%20#2-1990-jpeg.jpg
    158.3 KB · Views: 633
Back
Top