C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Overdrive relay

Old Jul 30, 2020 | 08:22 AM
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Default Overdrive relay

I bought a 1985 Corvette with the DN 4+3 about a month ago as a project, and I've been working my way through all the issues that came with it. One of the problems giving me special trouble is the overdrive relay - PO cut out the existing relay and bought a new one, but failed to provide any information as to the wiring order of the new one. Essentially, I have a bundle of wires that should go to the overdrive relay, and a new relay, with no way of knowing how they are all connected. Some of the wires are similarly colored, which will make this step especially interesting. I was hoping the good folks on this forum might either have a picture of their relay wired correctly, or better yet a wiring diagram that I could work backwards from to identify the pinouts for the relay. Thanks!
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Old Aug 1, 2020 | 06:11 PM
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Default Relay

GM changed to the new relays and connectors in late 88.
find someone who has an 89 or 90 With a factory service manual for the wiring of those relays
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Old Aug 1, 2020 | 06:59 PM
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Default Relay

The 89 Corvette switched to the 6 speed, so there aren’t any overdrive relays
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Old Aug 1, 2020 | 11:56 PM
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This might help, from an '87 but probably the same:



Last edited by jv9999; Aug 1, 2020 at 11:57 PM.
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Old Aug 3, 2020 | 07:14 AM
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Got everything soldered back together last night according to this drawing. This is exactly what I was looking for, thanks to everyone for the help!
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