NO Spark...... TBI 88 GMC 5.7 350

[Jims86]

correct.

do you have another coil around that you can try?

 

[HotRodPC]

I"m about to say he has a Bad ESC module. Anyway to test it???

 

[mhelms83]

do you have another coil around that you can try?

yes i do but the one that's on it is new, but ill try anyways

 

[HotRodPC]

I"m about to say he has a Bad ESC module. Anyway to test it???

Scratch that. Looking at the diagram, it wouldn't be that.

 

[mhelms83]

do you have another coil around that you can try?

i tried the back up coil and it didn't work. i tested both coils using an ohm meter per the haynes manual (chapter 5 section 6 illustration 6.12) and they both tested out fine.

 

[HotRodPC]

You said this EIM is new too right? Have you ohms tested it too to make sure it's not defective? I do believe AZ has a tool to test those too. I'd call to find out first before I drove it up there, but it's possible to have a NEW defective electronic ign module. I've seen that happen twice.

PS, and maybe I missed that part if you have already. This thread is getting long. I can see why you're losing your patience.

 

[mhelms83]

You said this EIM is new too right? Have you ohms tested it too to make sure it's not defective? I do believe AZ has a tool to test those too. I'd call to find out first before I drove it up there, but it's possible to have a NEW defective electronic ign module. I've seen that happen twice.

PS, and maybe I missed that part if you have already. This thread is getting long. I can see why you're losing your patience.

yes ive replaced the ign mod 2x over the last couple of days so its not that.

 

[HotRodPC]

So we're just about down to it has to be the wiring in the dizzy or the ECM huh? I'm still kind of trying to think through the ESC module thing, but I'm thinking the ESC isn't going to keep it from starting, and if the injectors are spraying, you'd assume that is fine.

I'm sure Jim is much more qualified on the TBI systems than I am, so wo getting to technical, I"m just trying to think of a simple things that may have been overlooked. And many times, that's what these situations turn out to be. Something minor and one of those things you'll kick yourself and say, Damn, I should have thought of that.

 

[mhelms83]

So we're just about down to it has to be the wiring in the dizzy or the ECM huh? I'm still kind of trying to think through the ESC module thing, but I'm thinking the ESC isn't going to keep it from starting, and if the injectors are spraying, you'd assume that is fine.

I'm sure Jim is much more qualified on the TBI systems than I am, so wo getting to technical, I"m just trying to think of a simple things that may have been overlooked. And many times, that's what these situations turn out to be. Something minor and one of those things you'll kick yourself and say, Damn, I should have thought of that.

yeah its always the simple things that get ya! the pick up coil in the dist is new and i tested it before i put it in. the ECM is the only thing that hasn't been tested/replaced. this is driving me crazy but i won't let it woop my ass.

 

[Jims86]

So we're just about down to it has to be the wiring in the dizzy or the ECM huh? I'm still kind of trying to think through the ESC module thing, but I'm thinking the ESC isn't going to keep it from starting, and if the injectors are spraying, you'd assume that is fine.

I'm sure Jim is much more qualified on the TBI systems than I am, so wo getting to technical, I"m just trying to think of a simple things that may have been overlooked. And many times, that's what these situations turn out to be. Something minor and one of those things you'll kick yourself and say, Damn, I should have thought of that.

Yeah, This is a real nut buster, and I dont want him to take it to a shop, just to do what we have collectively done aready, and charge him 4 hours diagnostic fee.
I dont think the wiring has been messed with, and this seems like an "all of a sudden problem".
What concerns me, is that he IS getting power from the key switch, to the coil, but not to the smaller gauge pink wire, going back to the distributor.
According to the Ign. mod diagram, that is the same circut in both plugs. like the bridge in the coild between the big and small pink wires is broken.
Mike, Do me a favor, and unplug the black connector on the coil, turn the key on, and see if there is any power at the prong where the small gauge pink wire plugs into?

 

[HotRodPC]

Yeah, This is a real nut buster, and I dont want him to take it to a shop, just to do what we have collectively done aready, and charge him 4 hours diagnostic fee.
I dont think the wiring has been messed with, and this seems like an "all of a sudden problem".
What concerns me, is that he IS getting power from the key switch, to the coil, but not to the smaller gauge pink wire, going back to the distributor.

Mike, Do me a favor, and unplug the black connector on the coil, turn the key on, and see if there is any power at the prong where the small gauge pink wire plugs into?

Right, so is it possible he's had some wire go bad in the dizzy, but how? And where do those wire get power from? ECM or ESC module? I agree, it's tracked down this far, it would be a shame to spend a fortune on diagnostics.

 

[Jims86]

Right, so is it possible he's had some wire go bad in the dizzy, but how? And where do those wire get power from? ECM or ESC module? I agree, it's tracked down this far, it would be a shame to spend a fortune on diagnostics.

The larger gauge pink wire is key ignition, the same on that plugs into our HEI caps. The smallmpink wire, is on that same circut, bridged inside the coil, and goes to the ignition module. the only other power wire to the ign mod, is the EST wire(the one we unplug to set timing) which is a 5v reference, that the computer controls, to tell the ign mod to advance, or retard the spark.
I am wondering about the pin in the plug for the small pink wire.
Mike, what work has been done on this truck, leading up to the day it wouldnt start, Before you started changing ignition parts?

 

[mhelms83]

Yeah, This is a real nut buster, and I dont want him to take it to a shop, just to do what we have collectively done aready, and charge him 4 hours diagnostic fee.
I dont think the wiring has been messed with, and this seems like an "all of a sudden problem".
What concerns me, is that he IS getting power from the key switch, to the coil, but not to the smaller gauge pink wire, going back to the distributor.
According to the Ign. mod diagram, that is the same circut in both plugs. like the bridge in the coild between the big and small pink wires is broken.
Mike, Do me a favor, and unplug the black connector on the coil, turn the key on, and see if there is any power at the prong where the small gauge pink wire plugs into?

yes i have power at the coil where the pink wire from the black harness goes. no power at the pink wire on the harness though. if that makes sense.

 

[Jims86]

yes i have power at the coil where the pink wire from the black harness goes. no power at the pink wire on the harness though. if that makes sense.

OK, set your meter to Continuity, and unplug that same two wire connector at the distributor, and probe both ends where the pink wire goes, and see if your meter screams...It may sound funny, but I am hoping it doesen't!

 

[mhelms83]

yes i have power at the coil where the pink wire from the black harness goes. no power at the pink wire on the harness though. if that makes sense.

* no power at the harness when its unplugged. but i think that smaller gauge wire brings power from the coil to the ign. mod. am i right?