Ignition module

[Old560]

I’m at a loss. This ignition module is the same type that used to use on Fords. This one is on a forklift. One day the forklift just died traced it back to the ignition module with no spark changed out the ignition module instantly fired right up and ran fine but an hour of run time later same thing no spark traced it back to the ignition module changed it out. Fired right up again ran fine. I’ve been through this three times now. The thing that really baffles me is the first ignition module. I put back on it, and it started running again. The other two are totally fried. The module it has on it now it’s acting like the timing is all messed up running rough and then dies out. Put the original module back on it totally fine. Any ideas at all on this one? I can’t just leave this module on it because it will die again. To the point where I let it sit for three weeks cause I’m totally sick of it. I just can’t figure out why it keeps messing up ignition modules.

 

[Oregon Tractor Jack]

Might change your ignition coil. I let the smoke out of a Petronix igniter due to a bad coil.

OTJ

 

[TN 2N]

I have an '89 Bronco that used to have a failure of the ignition module every few months, not quickly like yours. The last time, I noticed the tachometer was going crazy right before the module failed. After doing some research, I changed out the coil. Never had another module fail.

 

[Fritz Maurer]

That has all the classic symptoms of the old HEI distributors with the failing pick-up coil. Every time it cools off it starts working again.

You certain the engine isn’t overheating and causing a shutdown?

No guess as to why the other two are cooked , but you keep putting the old one on and it works for awhile… I have to think heat has something to do with it.

 

[used red MN]

You said “traced it back to the ignition module with no spark” Does that mean you did other troubleshooting and diagnostics to assure the module was the problem or no spark just automatically means the module is bad? Did you take an ohm reading on the pickup coil? Not sure what the spec is you will have to find that out. For sure wiggling the leads around it should not loose continuity. What is the charging system holding battery voltage at? Much over 14.5v may be high enough to effect how long your modules last.

 

[wore out]

I’m at a loss. This ignition module is the same type that used to use on Fords. This one is on a forklift. One day the forklift just died traced it back to the ignition module with no spark changed out the ignition module instantly fired right up and ran fine but an hour of run time later same thing no spark traced it back to the ignition module changed it out. Fired right up again ran fine. I’ve been through this three times now. The thing that really baffles me is the first ignition module. I put back on it, and it started running again. The other two are totally fried. The module it has on it now it’s acting like the timing is all messed up running rough and then dies out. Put the original module back on it totally fine. Any ideas at all on this one? I can’t just leave this module on it because it will die again. To the point where I let it sit for three weeks cause I’m totally sick of it. I just can’t figure out why it keeps messing up ignition modules.

"This ignition module is the same type that used to use on Fords."

FWIW, it's a Prestolite design, IH used them on pickups and Scouts, what engine is in your forklift?

I would Ohm out all the sparkplug wires and coil wire, checking for one that's "open".

If the wires are similar in resistance I would suspect the coil.

It's certainly possible the ignition pickup is failing, but that wouldn't "fry" the module.

 

[Old560]

You said “traced it back to the ignition module with no spark” Does that mean you did other troubleshooting and diagnostics to assure the module was the problem or no spark just automatically means the module is bad? Did you take an ohm reading on the pickup coil? Not sure what the spec is you will have to find that out. For sure wiggling the leads around it should not loose continuity. What is the charging system holding battery voltage at? Much over 14.5v may be high enough to effect how long your modules last.

I just followed the troubleshooting chart in the repair manual everything was testing good accept for the ignition module.

 

[MARK ROBKE]

What wore out said. Mark.

 

[rustred]

I’m at a loss. This ignition module is the same type that used to use on Fords. This one is on a forklift. One day the forklift just died traced it back to the ignition module with no spark changed out the ignition module instantly fired right up and ran fine but an hour of run time later same thing no spark traced it back to the ignition module changed it out. Fired right up again ran fine. I’ve been through this three times now. The thing that really baffles me is the first ignition module. I put back on it, and it started running again. The other two are totally fried. The module it has on it now it’s acting like the timing is all messed up running rough and then dies out. Put the original module back on it totally fine. Any ideas at all on this one? I can’t just leave this module on it because it will die again. To the point where I let it sit for three weeks cause I’m totally sick of it. I just can’t figure out why it keeps messing up ignition modules.

Sounds like it’s getting too hot. GM required the use of dielectric grease under them to keep them cool. Used to be the same symptoms. Vehicle would stop let it cool off and away you go.

 

[UncleTom]

If it has the hall effect pickup in the distributor, that could be it. Had a Ford Temp that would die on the side of the road and start back up. It was the pick up.

 

[Hobo,NC]

I’m at a loss. This ignition module is the same type that used to use on Fords. This one is on a forklift. One day the forklift just died traced it back to the ignition module with no spark changed out the ignition module instantly fired right up and ran fine but an hour of run time later same thing no spark traced it back to the ignition module changed it out. Fired right up again ran fine. I’ve been through this three times now. The thing that really baffles me is the first ignition module. I put back on it, and it started running again. The other two are totally fried. The module it has on it now it’s acting like the timing is all messed up running rough and then dies out. Put the original module back on it totally fine. Any ideas at all on this one? I can’t just leave this module on it because it will die again. To the point where I let it sit for three weeks cause I’m totally sick of it. I just can’t figure out why it keeps messing up ignition modules.

Page 4 is the wiring diagram for your module its simple 5 wires. TP85 was used on IH trucks and industrial equipment.

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I have a tester for it but cannot lay my hands on it. I was hoping to get the test sheet for this out of the tester box. I would use a logic probe to test the system I would be looing for it to switch at the stator and coil. Its simple and fast and a test that may not be performed with a test light.

The use of a logic probe and having spare distributors on hand is why I abandoned using a dedicated tester. It was easier to plug in a spar dist. and give it a spin. Those spare parts are somewhere and have not seen the light of day in 40 years. Those intermittent issues were hard to nail down. Don't overlook a rubbed through wire are a bad ground. I got to the point I would run a dedicated ground to the module to confirm I had a good ground. I would make sure I ran over every wire harness on them looking for a rub through.