4l80e Using Military TCM

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4l80e Using Military TCM

Postby Augi » Wed Jun 27, 2012 10:42 pm

All you guys out there with a 6.2 w/o the engine speed sensor bung in the timing chain cover who are planning on installing a 4L80E just got lucky!

Now I must admit I haven't tried this yet, but it all looks good on paper :)

Based on a thread over on steelsoldiers (thanks to colt45727 http://www.steelsoldiers.com/hmmwv/88447-4l80e-swap-s-2.html#post1160754) I did some more research and it looks like you really can replace the oil pump drive with a civilian part that produces the same number of pulses per crank revolution as the crank sensor.

What does this mean? Well now you can use the military TCM (which is way cheaper to get surplus than a $1000+ aftermarket computer) and you just need to add the double brake pedal switch, the TPS and bits of the harness (or make your own) and you can be up and running (a relay and maybe a circuit breaker for the 12v is a good idea too). It's also a plus for the purists to have less prominent civilian parts.

The crank speed sensor on the front of the 6.5 uses two wires (signal and ground). The sensor on the civy oil pump drive has three (+5v, signal and ground). Looking at the A2 wiring diagram I think that the signal and ground pins would be connected to the two existing wires for the crank sensor (349B for signal and 359F for ground) and then +5v would have to be supplied. The military TCM has a source of +5 for the TPS on pin d of the cannon plug (feeding wire 350A/B/C). With an added splice power can be run to the speed sensor as well.

Now you don't have to change the front of your engine!

P/N and picture: ACDELCO# 21597 or GM# 07849305
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Augi
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