ignition woes update

ibertone86

Daily Driver
Couple of weeks ago my 86 died at a stop sign and I have been unable to solve the issue. I have swapped coils, dist pick up and got a used icm on ebay with no result. Being a novice mechanic I am at my wits end and about to part with it.

No spark at the coil output
There is 12 volts to the coil
Ground check ok

I'd hate to buy a new icm but I am throwing parts at it at this point...suggestions?
 
Follow these steps

This is for late model...
Follow these steps carefully regardless if you think you've already checked before.

1. Insure there is a wire traveling from your resistor to the + side of the coil. (stock color = blue)
2. Insure there is a capacitor connected to the + side of the coil which is mounted to a grounded point.
3. Insure there is a green-jacketed YELLOW wire that is from the Bosch box connected to the - (neg) side of the coil.
4. Insure you have a 14" long black sheathed wire from the Fuel injection harness that also connects to the
- (neg) side of the coil. This connector is a male/female spade combo.

If you have these 4 connections made, your coil is wired correctly. No other wires should be on the coil.

5. Check that you have about 8 volts or more at the + side of the coil when cranking the engine over.
(Use a volt meter, + on the coil, - on the chassis) Note: Below 6V is not good!

6. Check for spark: Put a spark plug wire from the plug wire output of the coil to a spare plug you have kicking around.
You can rest a plug up against a ground point like one of the three 10mm nuts that hold your strut tower in-place.
The idea here is to see if the COIL is outputting spark while you crank the engine. Obviously you'll need help
from someone to crank the motor for ya.

If there is spark, the culprit is likely a defective distributor cap.
If no spark, you might have issues with the Bosch ICM. Before you come to that conclusion, Check:

7. A MALE (bullet connector) brown w/white stripe wire should go to the Bosch's White female wire. (has green sleeve.)
This is a Tacho signal and feeds through the Bosch out to the yellow wire in Step 3 above.

8. A FEMALE (bullet connector) pink wire goes to a blue wired male connector that splits to the Bosch ICM and the resistor that feeds your coil.

If Step 7 and 8 look OK, change out the Bosch ICM.

Hope this helps!

PS - I'm going to be posting a "how to repair a Bosch ICM for about $10 bucks" in a couple weeks.
 
Isn't there supposed to be a full 12 V going to the coil when cranking and then when the car starts it drops back to 9V in run position? Also a large alligator clip held in place on the test sparkplug with a hose clamp will make it so you can clamp onto a good ground and have both hands free.
 
Isn't there supposed to be a full 12 V going to the coil when cranking and then when the car starts it drops back to 9V in run position? Also a large alligator clip held in place on the test sparkplug with a hose clamp will make it so you can clamp onto a good ground and have both hands free.

I don't know about earlier cars, but late model cars with the Bosch ignition has the ballast resistor in the circuit at all times. No difference between running and cranking.
 
Mr. Dragon... NO to your question... but YES to the idea...

Mopar did exactly that back in the old days to ease starting of their cars.

It was simply done through the ignition switch and you could actually modify yours to do the same with one wire!

In the start position... the ballast resister was bypassed so a full 12vdc was sent to the coil which then provided a hotter spark. Once the key was released to the run position... power was reduced by the ballast resister and the coil operated on 9vdc or so.

It was in the 60's when I learned you could bypass the ballast resister and gain more power... and that was good for 1/4 mile racing. I also learned you could burn up the coil if you left it that way...
 
Everything that Bob said, BUT... you need to carry a...

spare ICM at all times anyway. (As Murphy might say... As long as you have it you'll never need it... and if ya don't, you will!)

Included in your Onboard Tool Box would be a few combo wrenches, a VOM, fuses, screwdrivers, pliers, a pint of brake fluid, oil, a COMBO RELAY, an FI ECM and of course the ICM. A gallon of water and jumpers cables goes without saying...

Sooooo, the FIRST thing I would do in YOUR case is to swap out the ICM with my spare... then go after everything else.

(Also note the condition of the terminals and if the ICM has been water fowled... insure the drain is clear in the pod as well...)

These things and more can be found at ridiculous and reasonable prices in the FS&W section... and you don't haveta buy everything at once. Post an ad with your WANTS and NEEDS and let folks offer the parts to you when you have the time and after you get over this hurtle.

Do let us know how you are progressing and we should be able to help some more if needed.
 
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