Author Topic: TCC lockup pin location  (Read 350 times)

Offline frotosride

  • Senior Member
  • ****
  • Posts: 1431
    • WFO CONCEPTS
TCC lockup pin location
« on: June 10, 2026, 10:18:25 am »
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
"Beat it like a red-headed ford"
1987 v10 Silverado(LQ4), 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6674
Re: TCC lockup pin location
« Reply #1 on: June 10, 2026, 12:53:04 pm »
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?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline frotosride

  • Senior Member
  • ****
  • Posts: 1431
    • WFO CONCEPTS
Re: TCC lockup pin location
« Reply #2 on: Today at 07:48:37 pm »
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?
« Last Edit: Today at 07:57:19 pm by frotosride »
"Beat it like a red-headed ford"
1987 v10 Silverado(LQ4), 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Offline frotosride

  • Senior Member
  • ****
  • Posts: 1431
    • WFO CONCEPTS
Re: TCC lockup pin location
« Reply #3 on: Today at 07:54:48 pm »
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
"Beat it like a red-headed ford"
1987 v10 Silverado(LQ4), 87 R10,83 K20, 83 cucv 6.2 Detroit
2006 Boulevard M109R 109 cid,2019 M109R BOSS
2009 Jeep XK, (future LS Swap)
GSXR 750 engine awaiting go kart

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6674
Re: TCC lockup pin location
« Reply #4 on: Today at 08:59:47 pm »
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!
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)