Gauge Cluster kills spark, PLEASE HELP

[Sprocket454ss]

I have a 1991 350ss, it was a 454ss with the 700r4, it still has the tbi automatic wiring harness still in it, but now it has a nv3500, I no longer have spark and i have changed everything, coil, cap and roter, and even plug wires. When you click the key to on the left turn signal automatically comes on without touching anything, so this made me think it was a ground problem, I have added three grounds going from the engine to the body and the engine going inside the cab. I was hoping that this would've fixed it but it still has the same problem, I knew it had to be something inside the cab, so I unplugged the fog lights same thing happened, no spark.I plugged the fog lights back in then I pulled the gauge cluster, this is where it gets confusing, with the gauge cluster out of the truck, it has spark, turns on, lights don't start turning on by themselves everything just works, but the second you plug the gauge cluster in, it kills it, and I lose spark. if any of you have ANY idea what is going on please, PLEASE tell me, I will try ANYTHING yes I have tried multiple gauge clusters

 

[DerekTheGreat]

Uhhh I'm no elechicken but it sounds like someone has been dickin' around with your wires. You'll want a wiring diagram to straighten stuff out..

Buuut, I'm posting because I had an '88 GMC C3500. It was the first vehicle I attempted to do the moonie to needle cluster swap on. I found a suitable cluster out of a '91 at a junkyard and for grins I slapped it on, some indicator lights such as the turn signal came on and such as the swap requires you to move a few around. Well, fast forward to me moving the wires, adding one for the tach signal and then having an issue with the BRAKE light staying illuminated with the new cluster. I went and dropped the old one back in.. I figured out the problem but created another without realizing it until I put the needle cluster back in- truck wouldn't start. Turns out if you let the tach signal go straight to ground you can smoke the coil and that's what I did. So maybe that's what you've got going on (among other things). What does the connector for your instrument cluster look like? Is it black and rectangle like? Is/was it the old style moonie set up and someone swapped it?

 

[Sprocket454ss]

Uhhh I'm no elechicken but it sounds like someone has been dickin' around with your wires. You'll want a wiring diagram to straighten stuff out..

Buuut, I'm posting because I had an '88 GMC C3500. It was the first vehicle I attempted to do the moonie to needle cluster swap on. I found a suitable cluster out of a '91 at a junkyard and for grins I slapped it on, some indicator lights such as the turn signal came on and such as the swap requires you to move a few around. Well, fast forward to me moving the wires, adding one for the tach signal and then having an issue with the BRAKE light staying illuminated with the new cluster. I went and dropped the old one back in.. I figured out the problem but created another without realizing it until I put the needle cluster back in- truck wouldn't start. Turns out if you let the tach signal go straight to ground you can smoke the coil and that's what I did. So maybe that's what you've got going on (among other things). What does the connector for your instrument cluster look like? Is it black and rectangle like? Is/was it the old style moonie set up and someone swapped it?

Perfect, there was a guy having the same problem as me, he tried to put in an after market tach and he said the white wire was grounding out and giving him alot of the same problems, I do have an old tach that is on the column, when i shoved the gauge cluster in the dash while it was running it shut off and burned the coil up, that was one of the worst smells I've ever smelt, yes it is a moonies cluster. So tonight I'm going to pull all the tach wires out and see if it'll fire

 

[Mark Gilbert]

You should be able to just remove the Tach wire at the coil under the hood. It should be white and have a single wire connector not far from the coil. the other connectors should have 2 or 4 wires...

 

[DerekTheGreat]

I'd remove all the Jim-Bobery wiring going on and get it back to stock. Verify all of the wires that are left behind are feeding what they're supposed to feed via the electrical service manual or wiring diagram for your truck.

Near the coil there is a spade connector for the tach signal, hopefully this is all the guy before you tapped into to try and run the aftermarket tach. I personally hate aftermarket tachs so I found the suitable 1990.5 cluster with a tach which looks like the 91-94 cluster but accepts the '88-'90 harness. They are out there in boneyards. I still find them from time to time and actually have a spare in my parts stash.

 

[Sprocket454ss]

Ok, I replaced the coil last night and with the gauge cluster still in it doesn't have spark, just like how it was, if you pull the cluster everything works, i pulled the tach out and everything in it. I replaced the oil pressure sending unit, because if it reads zero the engine shouldn't have spark, but that didn't fix it either, I did notice something last night though, I was messing with everything to see what would happen, and if i turn the hazards on, the fuel pump is turning on and off with it, I have it pretty much narrowed down to having a short somewhere, I will look some more tonight.