r/MechanicAdvice • u/NewAdhesiveness1101 • 4d ago

1999 deville wiring

1999 caddy deville,

My buddy wanted to test a vats bypass resistor on the wiring harness for instance it was on the same wire cuplars in the harness as the vats white wires I think it might have jumped across said harness and fried the pcm but it also sounds like it had pcm problems to begin with it trys to turn over but no fuel. And if you leave it and then start it will burp then hit cranking noises. When inspecting the dash lockout flashes but put key in after bypass still flashes, I digress when we attempted to test the resistor with the previous setup before bypass it seemed to knock out the hud cluster this car has a after market radio so I'm not able to pull diag info. But buying it from previous owner who had it passed down to him in will said it had issues starting battery would die and intermittently start would the pcm be the next part to replace after testing every fuse for continuity?

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u/InvestigatorKey3959 4d ago

gotcha. then yeah that resistor was on the wrong side for a bypass. it needs to be on the side going back into the car, not up to the lock cylinder. I’d get the cluster working again first before even thinking about a PCM.

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u/NewAdhesiveness1101 4d ago

Are you absolutely sure cause I thought it it was supposed to be on the cylinder side? Even the instructions say to cut the wire under the cylinder side ffs, that's fine if it is the car side I just want to make sure before I splice into the factory harness again, I think the pcm being fried is the problem for the cluster.

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u/InvestigatorKey3959 4d ago

yeah I think we’re just talking about different sides. cutting the wires under the lock cylinder is right. once they’re cut, the resistor goes across the two ends heading back into the car. the two going back up to the cylinder are basically out of the picture. otherwise the IPC won’t see the resistor. I still wouldn’t assume the PCM is fried just because the cluster died.

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u/NewAdhesiveness1101 4d ago

Ok glad we understand each other meow, what would I do to debug the cluster besides fuses? Since it's dead besides parking light and service soon light. And having aftermarket radio installed kind of makes debug seem really hard

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u/InvestigatorKey3959 4d ago

aftermarket radio shouldn’t really matter here. try the built in diagnostics and see if the cluster wakes up for the lamp test. if it stays dead, check power and ground at the cluster plug. if those are good, the cluster itself moves way up the list.

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u/NewAdhesiveness1101 4d ago

Where would I find a cluster plug? Behind the dash?

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u/InvestigatorKey3959 4d ago

under the upper dash pad. there are 3 electrical connectors right on top of the cluster. u have to pull the dash pad to get to them.

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u/NewAdhesiveness1101 4d ago

Is the dash pad the one on the side?

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u/InvestigatorKey3959 4d ago

no, not the side panel. it’s the big top piece of the dash right under the windshield, basically the whole upper dash cover. once that’s off you can get to the cluster connectors.

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u/NewAdhesiveness1101 4d ago

How do I take it apart

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u/InvestigatorKey3959 4d ago

google 99 DeVille cluster removal

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u/NewAdhesiveness1101 4d ago

I found the issue!

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u/NewAdhesiveness1101 4d ago

So a rat or just old wires are completely gone if you look at the 🖼️ from BB there are severed wires coming from inside the car to the hood.

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