Yeah GM was actually nice, they included four connectors with the coil module harness pigtail.

If you look at the picture above, the white wire comes out of the grey connector from the coil to the filter then the white wire comes out the filter and then that is that 6 feet !!! of white wire before I get to end pigtail with the spade/pin connectors.

 

That 6ft length of wire goes through the firewall to the IP and eventually the Tach

 

I believe I have the wiring figured out. I'll take another picture. Wish I had my iMac in the garage with me LOL...

 

First I want thank all of you, I could not have done this without you folks.

My baby is alive!

After so many failures, I took a break after wrapping it all up, then said go twist that key... she fired right up

Let her idle for about 10 minutes or so, seemed like a good smooth idle. It was up to ops temp so I drove around the subdivision several times, from idle puttering to normal driving and several WOT accelerations. I did this over and over a number of times when it got to about 207F coolant, I did notice that in gear at a stop I picked up a rougher idle but its idling around 600-650 rpms that seems a little low, but it I put in neutral or park and it comes up to like 750 rpms and is smooth again. I tried every way possible to make it duplicate the symptom but could not. It's very smooth in the hard accelerations too.

In the morning I'll take it for a drive on the interstate just to give more confidence that it's well again.

I replaced the ignition coil module harness, the tach filter, installed a new coil and ignition coil module. I did not install the ECM.

She fired right up oh was I happy... thank you Lord!

Here's a few images:

Here's my spliced new ignition coil module connector harness



The tach filter spliced and ready.



Here's the tach filter installed


Here's both tach filter and ignition coil module harness installed



Here it is with the heat tape installed (that was neat stuff)



And finished job.



All I can say is thank you all, thanks for your patience and standing with me on this.

One lesson for sure, I'm going to look for a $5-6K S10 or Ranger tomorrow at this major tent sale going on. I need a second vehicle.

Another lesson, learn more about electronics... geez it must have been the connector and also perhaps the tach filter. Since I replaced four components I don't know which one but all I do know is those four parts fixed it. Kind of what the DTC was saying open or short circuit.

I'm certainly grateful to have my girl back in action and to you all. Thanks everyone.

 

I got lost in the electronics discussion but what seems to be the upshot of all this? Was it a bad connection from the harness to the module? How about a final short summary of what the problem was? Thanks.

 

The post just before yours is the summary.

He was getting a DTC 41. Which means "short to ground EST (Electronic Spark Control)." Initially, we diagosed it as being a bad ignition module. This module, actually called the Ignition Coil Driver, is the part that amplifies the signal from the engine controller to the coil.

When he replaced the module, nothing happened.

Many posts and a few phone calls insued.

Which lead to the thought that a problem existed with the harness.

Jet then replaced the harness, coil and module, and life was great.

Lani - I am SO glad this is fixed!!! Can't wait to get a report on the REAL test - 417 here you come!!!

 

LOL thanks Andy....how did you know about the Greenway Toll road?

I-4 is closer though. I'll be a little apprehensive until the confidence factor returns. Did not like getting stranded!

 

Glad it is done and running.For someone who is not an electrician you did a beautiful job of splicing the harness. This thread is a definate keeper.Just goes to show how sometimes it is hard to see the trees through the forest especially in the ignition system.Did you play around with the bad plug? Did you check for continuity between the tach filter white wires to the ground?The initial spiking of the tach when the problem occured seems to indicate the filter.I still wonder which part was the culprit. Have fun

One additional question to all is during reasearch for this I found some info that indicated that ther are 3 different modules
92(and 93 I assume)
94(and 95 I assume)
96
Can anyone confirm this?

 

Thanks, and thank you for helping. Yeah I toyed with it a little bit it was really late after midnight but I did check continuity on the ICM plug, it showed good. I think besides that connector which may have been marginal (the new one snap tight and firm in the ICM), and the tach filter may have been marginal as Tom said. I wasn't sure what to measure on the tach filter, being a capacitor (I think Tom said).

Yeah when I got the tach filter from Ecklers it says for 92-93 and I believe Bogus told me the two year modules engine wise are identical.

Being lazy this morning I need to get moving and go for a drive. Stressful week as you have read.

LOL wondering if my mechanical luck has changed and I should do the fuel filter

Gosh if I weren't the center of attention, and was just following the saga, I know I would have learned alot. This was a good lesson to know more about what's going on in the system.

The only thing I didn't care for was that low rough idle in gear and brake when it was hot. Need to look in to that I wonder if the low idle can be adjusted. Also I have to talk to Chris about the ECM. If this one wasn't so nasty looking and that rattle issue, I would have swaped it out too just cause I had it and the other one is like 13 yrs of service. Maybe he can exchange it?

 

There was a question I had, just remembered: What does you folk's harness assembly look like with regards to the tach filter, is it outside the harness pigtail, is it taped up to the harness? My previous one just dangled, so the new one was installed similarly. Wondering if this is correct?

 

Mine is just taped to the outside of the harness.With it dangling that could have been the problem all along if it shorted to anything.Take a look at the wires very closely for any wear.All I am curious about with the filter is it should show a high resistance.If the cap is bad and shorted it will show none.Of course they usually fail opened but that in itself may not have caused any problem except an erradic tach.

 

Ok, at 20K Ohm setting white wire at connector terminal to white wire coming out of the filter is 15.30. White wire from filter to ground wire 1.00, and white wire in connector pin to ground 1.00.

Remember two white and a black wire come out of filter; one white goes to gray connector, the other goes to tach/ETBCM. Back goes the large end connector which mounts to the front of the engine.

Is that what you needed?

 

What still is not clear to me is how the car was at least able to start with the old ICM and not even start with the new ones. It seems like a bad harness/connection should be bad regardless of what module was being connected.

 

Yep the white wire should have some resistance if this is a Pi filter but I think you do not have enough resistance to gound.After all is settled down cut it open and let me know what you find inside.If it is a Pi filter you should have a little coil and a capacitor inside with a resistor going from one white to the other.I would think this is a bandpass filter that allows 0-8k frequencies to pass through and blocks the rest.

 

My GUESS is that the failing filter cause the old module to begin failing and made it able to recieve a degraded signal and still work while the newer one did not get a strong enough signal to cause it to work. I am just guessing won't be able to be sure until the filter internals are dissassembled and checked.

 

Remember? My brother lives in Sebring... I used to live in Delaware...

I would do ANYTHING to avoid I-4 during daylight hours - including dumping $5.00 worth of quarters into the Greenways toll plazas!!!

It was that or listen to the Phillips Philes and hope the traffic reports were not all full of wrecks by the John Young or OBT!!!

 

Yep I remember. Yep we have quite a sophisticated money machine to drive on roads here. At least that one is a nice smooth road to drive.

Ah Mr. Phillips, I use to listen to him a lot but during the last election he became so extreme liberal I couldn't stand it any more, well him and Moiré. Now I'm Hannitized. LOL

It's weird I-4 isn't too bad at night or during the early morning hrs on weekends. Just got to watch out for the troopers. Otherwise it's the I-4 parking lot.

My brother-in-law died in an accident on 417 at John Young a few years ago. He was the senior engineer building Disney's Test Track. The day before it opened they worked to finish it about 19 hrs he fell asleep on the way home at 2am. He commuted from Melbourne every day for like 18 yrs.

 

Oh I remembered something that is related to this post as well as another post I had last week regarding the use of dielectric grease vs silicone grease vs heat sink grease.

During my last install of the old coil module so that I could run some tests, I did not have any more of of the packet of silicone grease provided with the module. So I used dielectric grease.

This is something you do NOT want to do. I test ran the engine to pull clean codes again which was probably like 30 minutes.

The next day when I removed the ignition coil module/coil assembly to install the new parts, the old ignition coil module that I had applied dielectric grease was bonded to its heat sink plate. I had to tap it free with a screwdriver. After it came free the metal backing side along with a bunch of goopy stuff from inside was melted and it had separated. So it appears like dielectric doesn't assist with keeping the module cool, but does the opposite.

So I only used the packet of silicone grease GM supplies with the ignition coil module on its back side, and heat sink grease to mount the whole assembly to the engine.

 

Sorry to hear about your brother-in-law. That stinks.

As for Mr. Phillips... I need to tune them in on the web. I always got a laugh from him... and since I am not the least bit right-wing, his rantings won't bug me one bit. He has always been a bit left leaning, but I suspect the last election did a lot of polarizing that might not have occured with other candidates.

Good points about the dialectric grease. I hope the compounds you have on there are going to stand up! Did you clean the heat sink well?

 

Oh yes cleaned everything very well. I'm aware that this is intended to fill those microscopic holes in the metal to ensure and good contact, so I paid attention to that to ensure all old material was removed.

Yes that was a very sad time. Disney had two bus loads of people come over for the funeral. It was amazing. They also memorialized him which they rarely do, on the ride just as you pass through the heat test then to the cold test there are some rooms off to the right side with robot technicians in the room, on the wall there is his photograph.

LOL you left-coastie.