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casexxhemi
11-09-2003, 03:09 PM
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.

pastera
11-10-2003, 07:48 AM
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

Andy 94SC
11-10-2003, 08:43 AM
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?

Billabong089
11-10-2003, 09:35 AM
try a different heat sink compound....:-/

kevenj90sc
11-10-2003, 09:14 PM
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........???

casexxhemi
11-11-2003, 10:53 AM
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.

pastera
11-12-2003, 08:11 AM
I will start at the crank senor inputs then.

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

Aaron

MIKE 38sc
11-12-2003, 09:08 AM
Originally posted by pastera
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?

casexxhemi
11-13-2003, 12:14 AM
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.

casexxhemi
11-13-2003, 12:19 AM
O'Reilly has a tester, all were bad.


Originally posted by Andy 94SC
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?

casexxhemi
11-13-2003, 12:29 AM
The module you have is SCOTT90SC's module, not mine. I'll contact Scott & tell him to hit this sight.


Originally posted by pastera
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

Scott90SC
11-13-2003, 08:54 PM
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

casexxhemi
11-14-2003, 12:34 AM
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.

pastera
11-14-2003, 01:46 PM
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

Randeeofdawoods
11-14-2003, 06:29 PM
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.

Scott90SC
11-16-2003, 05:53 PM
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

casexxhemi
11-18-2003, 12:15 AM
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!!!!

eh488tke
11-18-2003, 02:40 AM
I will post what the guru finds with my car. Thanks to all who gave advise and thanks to Bill for the effort.

casexxhemi
11-18-2003, 03:01 AM
Sorry!! James:confused:

Scott90SC
11-18-2003, 05:03 AM
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

pastera
11-18-2003, 07:46 AM
Well, the output transistors on Scott's DIS are shot, as in melted.

All three look like a big blob of doped silicon. So something is holding those outputs on. I am going to program a microcontroller to fake a crank sensor and spout signal and test what the module is actually doing. Then I will replace the output transistors with something that will take a lot to overheat if everything else works.

Aaron

casexxhemi
11-19-2003, 12:18 AM
I'm not an electronic guy, but could the integrated relay control module that houses voltage inverters & the eec power relay be causing this problem. According to the schematic there are 4 diodes inside this thing. Could they be bad & feeding back to eec & burning up outputs in Dis.:(

Scott90SC
11-21-2003, 08:42 PM
Hey Aaron,

What are your thoughts on casexx's last post??
I have been thinking for awhile this could be somehow related to the EEC/IV Module does what casexx said make sense to you?

Thanks,
Scott

casexxhemi
11-22-2003, 03:15 AM
Hopefully we will get James' car to the gura this weekend. Wife is ready to throw a fit because a cold front is moving in. I will keep you informed of progress.:rolleyes:

eh488tke
12-01-2003, 09:25 AM
The car is at the shop (12/01/03), hopefully will know something mid week.
James

Scott90SC
12-01-2003, 03:01 PM
Thanks for the update James!! Please let us know what he finds!

Scott

It could be the difference between my car running again or not!

casexxhemi
12-09-2003, 12:23 AM
Talked to James @ work today & no word from shop yet.:confused:

Scott90SC
12-09-2003, 03:05 PM
Either this guy is swamped with work or this car his giving him fits, LOL

Scott90SC

casexxhemi
12-09-2003, 11:16 PM
James said that they haven't had a chance to look @ it yet. I don't know any shop that is that busy. Man, I feel sorry for the guy. I wish i could have found the problem, but i can't afford $10,000.00 in diagnostic equipment. A week @ a shop is a long, long time.:confused:

SC-71 TBIRD
12-10-2003, 12:57 AM
This is a very interesting thread, but I do have a question. Is it possible to test a DIS for problems with a DVOM? I am not sure if my DIS is going bad but reading this thread is making me wonder. I had just replaced the cam sensor today and the car (seems) ok so far. I would like to change the DIS eventually since it looks like it has not been changed in years, and or it (could) be going bad. But to satisfy my concerns I would like to test it first.

casexxhemi
12-11-2003, 12:18 AM
If you have an O'Reilly near you, call & ask them if they have a dis module tester. They are pretty neat, it heats the module & runs it through a series of tests. FOR FREE!!:D

SC-71 TBIRD
12-11-2003, 10:41 AM
I have a new question. Where can I purchase a new DIS module?
I'd checked R & S Strauss and Autozone in NY but they do not have the part. I do not want to go to a stealership and most likely those bozos will not have the part either. Ordering the part is preferably not a option.

dkmac
12-11-2003, 11:11 AM
SC-71 TBIRD you can buy a new one at Advanced Discount Auto. I bought a new one from them almost a month ago and have had no more problems. Just make sure that you clean the old thermal compound before you install the new DIS, be sure to use alcohol to clean with "prefered methoid". Before you install the new DIS USE NEW THERMAL COMPOUND! It can be found at your local radio shack or computer store. If you don't use this it will cause the new DIS to overheat, becouse it will not be able to transfer heat. Kinda Like a CPU and heat sink in a computer. Oh I only paid 99 dallors for my new DIS from Advanced Discount. Just tell them that Auto Zone has it for $99 and they will match the price. Well at least they do here in Jax. Well I hope this helped. God Bless and good luck.

eh488tke
12-11-2003, 02:53 PM
Scott
Finally, Jerry's Automotive is going to start on my car. I will keep you updated as the saga continues to unfold. They are a very busy shop.
James

Scott90SC
12-11-2003, 07:48 PM
Cool thanks I cannot wait to here what he finds!! I just hope mine is the same!

Scott

eh488tke
12-16-2003, 12:13 AM
Still no word, but it is being worked on. Maybe no news is good news.
James

eh488tke
12-16-2003, 11:38 AM
Scott,
Just got word from the guru, he has fixed the car. He has drove the car around 15 miles today and has not knocked out a module (my jaw is on the floor). He wants to keep the car another day, drive it home, around town, yada, yada and verify that it is fixed. Bottom line, he said the coil pack (overtime) has built up a high resistance and is what is knocking out the DIS modules. He said he checked everything around the module and coil pack and it all tested out ok.

I asked how he could tell if the coil pack had high resistance when we checked the coil pack and it tested out ok according to the manual. He said, you can test it (somehow) going to ground not going to ground, I got lost here. If anybody knows how he did this, please explain. All I know is what he said, it may be ok not going to ground, but due to the high resistance that has been built up, it will go to ground and knock out the DIS module.

I guess my suggestion would be to replace the coil pack and DIS module with Ford OEM. Hope this helps. I will see if I can't pull a little more info out of JR when I pick up my car. Who knows, I will try to have Bill (casexxhemi) there.

Thanks
James

Scott90SC
12-17-2003, 05:53 PM
Cool I am glad your is up and running! I am not sure about mine but what the heck I will give the Stealership a call and get the parts comming!

Scott

casexxhemi
12-18-2003, 12:31 AM
Man; Scott can you believe that! Talked to james today @ work & he told me what it was. Thats why I spent so much time online trying to find the correct Ohm values. Man I feel like a duma$$.I hope you have good luck with yours.
When Jame's module went out 3.5 yrs. ago I replaced the coil pack first because it was shot. Ohm values were way off. Then we had to wait for ever to locate a module.
Let me know what Happens? Bill :D

pastera
12-18-2003, 10:18 AM
What was the impedance of the coils?

The high resistance sounds like an open secondary which should fry a single ouput transitor. The unit I looked at has all three outputs MELTED which should not have occured (except if the failed coil was the one used to monitor the primary current).

Aaron

eh488tke
12-18-2003, 03:01 PM
Aaron,
If I can't get warranty out of my last module, would you like to take a look at it to see if it is simular to Scott's?
James

Scott90SC
12-18-2003, 04:45 PM
Just so everyone knows my situation my coil is brand new (July car has not ran since August) from Advance Auto Parts. I cannot think of the brand name currently but it is not Ford factory equipment, so if it is the cause of all of this trouble, I wasted lots of money because of an aftermarket part for this car! I will most likely have close to $750 in this mess, so if the factory parts fix my car we get back to the old addage you get what you pay for!

I unfortunately have spent too much on Christmas so I will not be able to order from the stealership until my next payday, 26th. I will however let all of you know as soon as it is back together if it worked or not.

I just remembered the brand name on the coil GP Sorrenson (not sure that is spelled correctly) $95 part sounds like it may have been a big waste.

Maybe that coil could have somthing to do with the miss I was chasing back in July "LMAO" Imagine that purchase a new coil to try and get rid of miss (did not fix miss) then less than a month later loose the DIS and here it is late December and the car still does not run!

Sorry for babbling on I am getting pretty upset so I think I will close for now.

Merry Christmas to all of you wonderful T-Bird lovers!!!

Scott90SC

pastera
12-18-2003, 06:34 PM
Scott

I will ship you my coil for testing - it's an 89 and the engine was running until I had a little trouble with a plug change (stuck in head).

If you want it, let me know and I'll send it out.

Aaron

pastera
12-18-2003, 06:46 PM
I just reread James' post. If the coil is leaking to ground it can easily kill the DIS. The impedance on the secondaries gets reflected to the primary, if there is leakage to ground, the primary sees a low impdance and the current rises to a much greater level than the EEC commands. This causes the output transistors to overheat and actually melt until they short out.

I would have a lot more time to study this (and maybe fix these modules) if the wife hadn't used her little Jetta to play tag with a couple of large Ford trucks - Yup, she bounced off not one but two trucks (neither of which had more than scratches on the bumpers) and took out both fenders, the bumper, and the passenger's side front door.

Anyone know of a good site to learn autobody?:(

Aaron

eh488tke
12-22-2003, 12:23 AM
Scott,
Jerry at Jerry's Automotive installed Borg Warner Coil Pack and DIS Module on my car. Jerry said he has good luck with those parts, pluss the warranty is better than Motorcraft. The car is feeling very strong, at least, compared to the mini van I was driving.
James

Scott90SC
01-10-2004, 10:13 AM
Hey all,

I have not been able to order parts for my SC yet. Our Expedition has developed a problem and it is the family grocery getter so it needs to be fixed first.

I will update you as soon as those parts are ordered though.

Thanks,
Scott90SC

Paul93SC
01-10-2004, 01:23 PM
I asked how he could tell if the coil pack had high resistance when we checked the coil pack and it tested out ok according to the manual. He said, you can test it (somehow) going to ground not going to ground, I got lost here. If anybody knows how he did this, please explain. All I know is what he said, it may be ok not going to ground, but due to the high resistance that has been built up, it will go to ground and knock out the DIS module.

Well, I'm baffled... this makes no sense to me at all. If the windings developed a higher resistance than normal, less current would flow through the DIS, not more.

The primary coil windings always have +12v applied to them... it's the DIS module that "grounds" out each winding allowing current to flow (see attached diagram below). If there was leakage to ground at the coil pack, this might result in burned out coils (?).

In a nutshell, how a coil functions is to store energy in the core by building up a magnetic field. When the DIS first begins to allow current to flow, the impedance of the primary winding is high. As the coil core begins to saturate (the point where no more magnetic energy can be stored), the impedance of the winding begins to drop and current flow increases dramatically (see upper right insert in the diagram).

At this point there is no reason to keep the current flowing because no more energy can be stored in the core AND current levels become excessive.

Now, if the coil primary winding was too small for the circuit, then saturation would be reached sooner and excessive current would also begin sooner (assuming the dwell was the same in both cases). This could happen if the primary windings shorted out to each other, or the windings were too small to begin with (aftermarket changes to the design).

Those DIS output transistors are not exactly perfect conductors and have to dissipate power when switched on. The longer they're conducting current the hotter they get (thus the reason for a heatsink). These burn out over time in every early model car, so it probably wouldn't take much of an extra load to kill them even quicker. It was dumb of Ford to mount them where they did... which they finally realized and made a design change in 94. How many DIS modules have you heard go bad in the 94-95's?

BTW, I re-read all your posts and you didn't say whether you were running an OEM coil pack or some sort of aftermarket replacement (?).

kpatton
06-02-2005, 05:16 PM
Here's a thought....

The only things that usually kill an electronic part are high voltage or heat..
Heat sink grease that you used should have taken care of the heat.

Now...
What voltage is your alternator putting out? A dead regulator causing the volatage to be Too high may be culprit..,then there must be a voltage regulator somewhere to give the reference voltage to the cam/crank sensors...which all feeds to the dis module. I traced out the cam sensor and if I remember correctly it connects to the DIS and the ECC.., I'm thinking that the regulator may be in the DIS...and the signals are fed to the ECC.. I may be wrong though..

Mike8675309
08-20-2006, 07:49 PM
Oldie but a goodie... did this ever get resolved?

eh488tke
08-22-2006, 05:23 PM
It turned out to be the coil pack that was shorting out the DIS module. We could not tell that the coil pack was bad, we compaired the resistance of a new coil pack to the one that was bad, meter readings were the same. Bottom line, if DIS module keeps shorting out, change the coil pack.