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Old 05-23-2007, 06:55 AM   #1
Tink
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Wiring for lock-up converter on 85 THM350?

We recently replaced the 305 in our 85 Silverado with a rebuilt one from a 70s car. When we removed the old 305, we ditched a lot of the computer and emissions BS. However, it seems that we must have gotten rid of whatever fed/controlled the lock-up torque converter on the TH350 - it doesn't seem to be working now. Can someone here tell me what the wires are that feed it and what not?
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Last edited by Tink; 05-23-2007 at 07:31 AM.
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Old 05-23-2007, 06:37 PM   #2
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Re: Wiring for lock-up converter on 85 THM350?

Okay, I don't know if this will help or not, but I have attached a couple of wiring diagrams for an 85 305. I know that you have replaced the 85 with one out of a 70's car. I'm not a 100% sure, but I think that the ECM that controls the engine also controls the trans. Also, over in FAQ on the secound page of Truck Tech there is a post that says Turbo 350c Lock Up Wiring by dhill it has a wiring diagram for the trans, but I don't know whether or not it will help you if it went through the ECM.

Good luck

Al
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File Type: pdf 85 Chassis Electrical 1.pdf (74.4 KB, 142 views)
File Type: pdf 85 Chassis Electrical 2.pdf (71.1 KB, 111 views)
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Old 05-23-2007, 07:30 PM   #3
Ivan D.
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Re: Wiring for lock-up converter on 85 THM350?

Is it possible to run the lockup to a switch that you can engage manually?
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Old 05-24-2007, 12:21 PM   #4
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Re: Wiring for lock-up converter on 85 THM350?

Yes you can hook it to a manual switch. I don't remember which pins to hook up to on the trans though. There are a few sites around that explain it really good. I will try to remember what they are.
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