Recent Posts

1

Electrical / Re: TCC lockup pin location

« Last post by bd on June 12, 2026, 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!

2

Electrical / Re: 87 R10 dual tank pump issue and hot fuel module

« Last post by Ocho on June 12, 2026, 08:25:46 pm »

Yes. The in tank fuel pump comes on with key on, regardless of tank selector switch on the dash. The right tank operates as it should. Switch to right tank and the pump comes on. Switch to the left tank it goes off but the left stays on continually. There is key on power from those two tan wires. One goes to the dash selector switch and the other to the left pump. That's where I'm confused. Should there be two team wires coming out of that one bulkhead terminal?

3

Electrical / Re: TCC lockup pin location

« Last post by frotosride on June 12, 2026, 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

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Electrical / Re: TCC lockup pin location

« Last post by frotosride on June 12, 2026, 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?

5

Electrical / Re: TCC lockup pin location

« Last post by bd 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?

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Electrical / TCC lockup pin location

« Last post by frotosride 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

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Electrical / Re: 87 R10 dual tank pump issue and hot fuel module

« Last post by Captkaos on June 10, 2026, 08:49:45 am »

When you say the left tank comes on, do you mean the fuel pump or?

This part is confusing to me, what exactly do you mean by this:

But I'm bypassing the solenoid valve for the fuel selection Only , it's still being used for the fuel gauge readings.

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Electrical / Re: 87 R10 dual tank pump issue and hot fuel module

« Last post by Ocho on June 09, 2026, 09:53:51 pm »

Left tank pump i should've said

9

Electrical / Re: 87 R10 dual tank pump issue and hot fuel module

« Last post by Ocho on June 09, 2026, 09:51:23 pm »

Let me get those details for your. Thanks. The problem I'm having is a soon as I turn the key to on,  the left tank comes on regardless of dash switch position.

10

Electrical / Re: 87 R10 dual tank pump issue and hot fuel module

« Last post by Captkaos on June 09, 2026, 03:51:42 pm »

I am going to have questions first for a better understanding. 
What issue are you chasing?
Was your truck spec'd for above 8500 GVW and has a Hot fuel module?

Those appear to be tan/white wires coming out of that terminal and it should not an issue since the are connected/spliced anyway.  What are the numbers on that terminal for Brown, Dk Grn, tan/white, X, pink, yellow and lt grn?
120 tan/wht = fuel pump relay
both in-tank pumps and the fuel selector valve
920 tan = left tank pump & selector valve,
921 gray = right tank pump & selector valve
150 blk = ground

The dash gauge switches between tanks by the selector valve. 
30 pink = gauge
930 pink/white = left tank sender
931 pink/black = right tank sender