73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Electrical => Topic started by: frotosride on June 10, 2026, 10:18:25 am
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Looking for where the torque converter lockup (+) purple wire pins in at the firewall. Honestly can't remember if it is a separate plug/connection or if it was originally on the main bulkhead for the fuse panel. It's been so long that I can't remember where I de-pinned it from.
1987 V10 Silverado 700r4
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The purple wire (Ckt 420) supplies I+ to the TCC solenoid from the brake switch. It routes through the firewall bulkhead connector as shown. Is this the wire you are questioning?
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Thank you, I swear I looked through all of the diagrams listed for '87 but couldn't find this diagram. The ones listed/pinned say 1987 but are printed for 1988 and have more pins. I almost just put it back together where ever I had a free spot. But I stopped so I can do body mounts. I did find #420 on the other chassis diagrams but the bulkhead connectors didn't look right.
Did you pull this sketch from the ones pined above?
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I have kept the brake switch without vacuum hooked up. I'm letting the Terminator handle (-) control for the relay and the brake switch (+) for tcc lockup. Also plan to use the 4th gear grounding circuit as input for possible future tuning configs. Thanks again
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Did you pull this sketch from the ones pined above?
I compiled the diagram from two separate diagrams illustrated in the '87 factory wiring manual. It took a minute because there are circuit omissions in the diagrams that obstruct easy correlation. You're welcome!
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Oh, you read the big words... That's not my style, I prefer pop-ups. But seriously thanks and now I have to find it!
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Terminator as in Holley?
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Yes sir
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Terminator as in Holley?
As in Arnold
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Terminator as in Holley?
As in Arnold
Funny Vile ;D
Curious are you using (assuming) Terminator (not X Max) and you are wanting to lockup the converter on the 700R4?
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Sorry been busy, my daily decided that power steering doesn't belong in the hydroboost anymore and while running the engine to prime the system the water pump decided to stop weeping and flood the driveway.
Anyway, yes I allowing the Terminator (not the x, but technically they are the same you just have to download a config and build a harness) to control the lockup via the (-) switching power for a relay. I'm doing this because within the config you can set many parameters and add inputs as needed to edit triggers. Also I can use TPS and not run another vacuum hose through the firewall. Having a vintage air set up helps that too
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cool thanks for the feedback. The X vs X max are much different however: the X Max will do Drive By Wire and Automatic trans control