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Discussion Starter · #82 ·
Good question, one set is normally open and one is normally closed. One will be used for the ECM to know when the clutch is pushed to drop the throttle to make it easier to shift, and the other is to pause the cruise control. D850A is the ACD# and the GM # is 25524845. I chose to get a GM switch instead of aftermarket after seeing some not so good feedback on an aftermarket brand switch.
 

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Thanks! When the pedal is not pushed in the cruise circuit is closed and the circuit to the PCM is open, correct? I've been looking for a switch that would work for my LS/TKO swap and this looks to be just the ticket.
 

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Discussion Starter · #84 ·
Thanks! When the pedal is not pushed in the cruise circuit is closed and the circuit to the PCM is open, correct?
Backwards. The cruise control side works just like a brake light switch, when the pedal is pushed the circuit is closed get's the 12 volts (yellow and white wire on Dakota Digital CRC-2000). The ECM side has 12 volts until the pedal is pushed then the circuit opens. At least that's the way it works on the LT4 and 5 engines. This switch is used to unlock torque converters when the brake is pushed on conversions too I believe.
 

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Thanks Steve. My swap is using a factory PCM from an 04 Avalanche. I'm mainly focused on the pcm circuit so I'll have to check the schematics to see which contacts mine needs to use. Do you have numbers for the wiring connectors?
 

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Discussion Starter · #88 ·
No need to look for pinouts, I was just wanting to know about the 2-wire plugs but I just reread your post and see that you found them on an old harness.
I'm using a new harness, those plugs came from the old harness brake light and clutch safety switch on that harness
 

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I have a LT4 with a manual transmission. I do not have my wiring harness yet, but I downloaded the instructions. The GM crate engine control system kit instructions state to install a switch on the clutch pedal. When the clutch is depressed, a signal is sent to the ECM to briefly disable fuel which will decelerate the engine to make shifting the transmission easier.

The instructions have the ECM wiring pin outs. ECM, cavity 64, circuit C 20, yellow wire, is labeled Top of Travel Clutch Switch.

I cannot find any references for a brake switch being wired to the ECM. Do you think the brake switch is only used for an automatic transmission or, the LT4 and LT5 are a different in this aspect?

Edit: I think you answered my question. The brake pedal switch deactivates the cruise control.
 

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Discussion Starter · #90 ·
I have a LT4 with a manual transmission. I do not have my wiring harness yet, but I downloaded the instructions. The GM crate engine control system kit instructions state to install a switch on the clutch pedal. When the clutch is depressed, a signal is sent to the ECM to briefly disable fuel which will decelerate the engine to make shifting the transmission easier.

The instructions have the ECM wiring pin outs. ECM, cavity 64, circuit C 20, yellow wire, is labeled Top of Travel Clutch Switch.

I cannot find any references for a brake switch being wired to the ECM. Do you think the brake switch is only used for an automatic transmission or, the LT4 and LT5 are a different in this aspect?

Edit: I think you answered my question. The brake pedal switch deactivates the cruise control.
Yes, the brake light switch deactivates the cruise control and also the set of contacts on the clutch switch that I used which is an open circuit when the clutch is not pushed deactivates the cruise control. If you didn't have this switch, the engine would rev up when you push in the clutch to slow down to try to maintain speed.
 

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Damn! I was going to offer to trade you my 396 for the LT5!
Happy April "Foolers" day - April 2nd.
Brett 🚀 🚀 🚀
 
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Discussion Starter · #96 ·
So back to the real world past April 1st, working on moving some things around on the harness and replacing the PIA hard plastic flex covering so we can work with it a bit more. What's wrong with this picture?
Gadget Communication Device Telephone Office equipment Electronic engineering
 

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Discussion Starter · #98 ·
Looks like you have to double check everything. Wrong rated fuses installed in 2, 9, 13 and 14.
We have an extra 25 and short a 10amp fuse. Glad we caught it, hope the diagram is right! :)

Drive system hung so we can finish up the engine side of the wire routing and reconfiguring. Need to move the charge cooler pump to the opposite side of the engine in the bundle and a few other adjustments.

Automotive tire Motor vehicle Automotive design Blue Automotive exterior
 
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