Knocking out DIS modules Left & Right

casexxhemi

Registered User
This post was originally under Dis coil ohm values. But thanks to the guys on this site, I agree that ohm values for primary coil should be .8 ohms. Now lets get down to the nut cuttin. we have replaced 4 dis modules, checked all wiring. What would keep knocking out modules? I will stay on this post to keep centralized on the dis problem.
 
I have the bad DIS module but with my wife in mid-terms I have been too busy to do much.

I did pull the cover and visually inspect the unit and did not find any obvious damage. I also am trying to get some info on the IC (motorola) so I can trouble shoot the module better.

Hopefully, I will be able to remove the potting compound(clear sticky gunk) this week and check everything out this weekend.

Aaron
 
Are you POSITIVE the DIS modules are going bad? I mean, have you tried any of these "bad" ones on a good car to make sure they no longer work?
 
are you using heat sink compound? or are you using dielectric grease..... make sure it is truly heat sink compound and not dielectric grease, i've seen cheep modules come with the wrong stuff in the box (not necessarily for an SC, just in general) I work at a NAPA store and we have a 'premium' and a 'value' line of ignition parts. The cheep...er ...i mean 'value line' modules come with the wrong stuff in the box, while the 'premium' modules have the right stuff in there......just a thought. Also i think it's possible for a bad cam sensor to take out a DIS module......my DIS went bad (we have a machine at work to test them, and it truly was bad), a new one fixed the car but in a month or so it was acting up again....hard to start sometimes, just like before......kept getting worse, module tested bad again so i replaced it under warranty, but the car was still hard to start.....replaced the cam sensor and no more problems, that was in March...... So i'm thinkin' the cam sensor might have taken out the original DIS and the first replacement one........???
 
Knocking out dis

Using Radio Shack heat sink, we have changed the cam & crank sensor. Ohmed out wiring. Going to pull plugs for the hell of it, When the car did start, it ran fine. But putting it under a load may be more than the wires & plugs can handle. Plugs and wires are 3 years old. All old modules have tested bad @ O'Reilly. We didn't start knocking out Dis Modules until we replaced crank sensor. Air gp set to .018 to.020.
 
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I will start at the crank senor inputs then.

Can you pull the sensor and check its wiring harness for damage?

Aaron
 
pastera said:
I will start at the crank senor inputs then.

Can you pull the sensor and check its wiring harness for damage?

Aaron
Aaron does the crank sensor use the 5 volt refference like the other sensors? Could it be possable that there has been an internal short or something that could cause the crank sensor refference voltage to go higher thus burning up the modules?
 
Knocking out Dis Modules

Cam & crank sensor are new. (borg warner) I've talked with 3 Ford tech's & they all agree that the cam & crank sensors need to be replaced with original Ford parts. They are different than motorcraft igntion parts bought @ parts stores (better quality & modules don't rattle). I will replace cam & crank sensor when i get off work tomorrow night. $54.00 cam / $96.00 crank, my cost.
 
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Dis

O'Reilly has a tester, all were bad.

Andy 94SC said:
Are you POSITIVE the DIS modules are going bad? I mean, have you tried any of these "bad" ones on a good car to make sure they no longer work?
 
dis module

The module you have is SCOTT90SC's module, not mine. I'll contact Scott & tell him to hit this sight.

pastera said:
I have the bad DIS module but with my wife in mid-terms I have been too busy to do much.

I did pull the cover and visually inspect the unit and did not find any obvious damage. I also am trying to get some info on the IC (motorola) so I can trouble shoot the module better.

Hopefully, I will be able to remove the potting compound(clear sticky gunk) this week and check everything out this weekend.

Aaron
 
Are you POSITIVE the DIS modules are going bad?
I did not have a good car to test my "Bad" modules on but by replacing them the car would start right up. My original DIS died under load, the second died in the driveway at ildle after about 15 min. The third, the one Pastera has, idled for about 20 min then died under load (not heavy load) about 1/2 throttle in third gear first trip down the street.

try a different heat sink compound....:-/
are you using heat sink compound? or are you using dielectric grease
Used Heatsink compound purchased from my PC parts outlet designed for Processor to Heat Sink. Also used Radio Shack Heat Sink Compound. Not Dielectric greese.

Also i think it's possible for a bad cam sensor to take out a DIS module
My Cam sensor was replaced after the first module went and before the last two went.

When the car did start, it ran fine. But putting it under a load may be more than the wires & plugs can handle. Plugs and wires are 3 years old.
My Plugs and Wires are new in July direct from the Stealership

Cam & crank sensor are new. (borg warner) I've talked with 3 Ford tech's & they all agree that the cam & crank sensors need to be replaced with original Ford parts.
My Crank Sensor has not yet been replaced car ran fine with it for 1 1/2 yrs before the DIS issue

I think this should catch me up with the rest of the posts here, Me and Casexxhemi have talked on the phone about this and the only truly common denominator in this is the bad DIS's,
1.) I have newer plugs and wires his are older.
2.) He has replaced the crank Sensor I have not.
3.) He has ohmed out his wiring, I have used two seperate DIS harnesse's.
4.) His car is a 92 mine is a 90.
the only things I think we have in common is that I think we both have replaced the coil and cam sensors.
I will be suprised if the factory ford crank and cam sensors fix this problem. But I hope I am wrong! I will buy mine next week if it does.
The one thing I am curious of is the EEC / IV Module which I believe feeds the DIS its power could they be bad and sending too much juice and frying the DIS's?? Maybe this could be the common problem in both cars?? Or maybe there will not be a common problem. All I know is it has taken alot of money to go nowhere for both of these cars!

Thanks for all of your help and support!
Scott
 
Dis modules

Amen to that. I'm replacing the cam & crank sensor now. Found yellow & red wire coil #2. Trying to melt to yellow & black coil #1 in wiring loom. Ohmed wires no resistance, but replaced wire, soldered & heat shrinked.
 
The melted wires are definately showing the DIS is not regulating the "on" time for the coil current.

It sounds like a SPOUT malfunction but the DIS module is supposed to sense this and correct for it. If you have a spare DIS harness pull the SPOUT wire and see if the harness heats up while running. You shouldn't damage anything if you run it for 30 seconds.

I will look at the output transistors and see if all three are smoked. If only two are bad I can try to find a replacement transistor and repair the unit. That way you would have something to troubleshoot with.

I did notice a heat signature on the base plate under two of the output transistors.

Aaron
 
Outta the ball park here, but what part did you replace the coil with? Was it an original Ford part? It could be the coil pack is bad and drawing too much current.through the dis module causing the problems. I can't remember if there is a direct connection or not. I don't think so, but if the car ran fine before the coil pack and now doesn't, I'd lean towards that.
 
CaseXX,
Did you get the crank and Cam sensors replaced?? Just wondering if you fried another DIS?? If it worked I will order mine tomorrow!

Scott
 
DIS

Didn't work. Replaced cam & crank sensor with original Ford parts.Did a koer test with 4000e. Went through cylinder balance perfect. Got a pass 11. Shut the car off, unhooked monitor. Went inside to wash my hands to test drive. Came back to garage and NO-START. It's going to a guru here in Edmond, OK. later this week. I'm Done!!!!
 
I will post what the guru finds with my car. Thanks to all who gave advise and thanks to Bill for the effort.
 
Well at least you have a guru to take it to! I don't even have a Ford dealer in Wabash anymore! Last one was triple floorplanning and got himself in a whole bunch of trouble! LOL
Hopefully your guru will be willing to give up all the details it took to fix your car!!

Thanks,
Scott
 
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