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
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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
I have yet to prove my theory but from my poking around it seems as though the drivers are in both boxes. I haven't verified the pins but the x has plenty that aren't used.The major one that the x absolutely might not have is likely drivers for DBW. I'm currently using a 4l60e config for my 700 so I can use the VSS signal for special functions. Maybe one day I'll test this out by pulling a config from the global and seeing if the pins work. Wouldn't be the first time a manufacturer made something exactly the same but marketed different.
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I am using a Terminator X Max on my daughters 2011 Mustang that I LS swapped with a 4L60E, I ran out of I/O fast, it only comes with 4 fully programmable inputs and 4 fully programmable outputs.
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I am using a Terminator X Max on my daughters 2011 Mustang that I LS swapped with a 4L60E, I ran out of I/O fast, it only comes with 4 fully programmable inputs and 4 fully programmable outputs.
Yes, the outputs are definitely the things I'd want more on for the basic unit. They do have an I/O expansions that simply plugs in and uses can bus just like the everything else. I just decided to limit myself and not spend the money. At least that'll be one more slightly reliable Trashstang on the road.
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Since you're using a Terminator I figured I'd share a lesson of the day. .. ;)
If you have the latest version, at least V3 Holley made a output test mode. The HP and Dominator have this mode to and the same rule applies.
This mode is like using a scan tool for OBD can bus operation of components. It'll allow you to say test the coil or injector driver's from the ECU/Terminator.
Lesson: inside the software you can test the fuel pump but nothing tells you that the Holley circuitry is designed to not fire injectors if the fuel pump relay control circuit (really-pins 85/86) doesn't complete a path to ground as a low trigger input for the injector driver's.
So basically you have to click the box to turn the fuel pump 'on' or no power for the injectors.
I didn't want the draw power the whole time or the possiblity of poring fuel down a cylinder so I pulled the fuse for primary power to keep the fuel pump off. You could pull the relay and put a small resistor as well.
Hopefully you don't have to use this feature but if you do, now you know..but will you remember? :o