Gmt400 to gmt800 multifunction switch swap,diagrams needed

[eric_503]

Looking for the diagram for a 95-98 multifunction switch, All I can find are ones labeled 88-98 and they arent the same pin outs.

The switches are physically the same, plugs are also the same. But the pin outs are different.

Plugging it in without modifying anything results in the mist function working like it should, but also spraying washer fluid, and wipers on high work like they should but also spray washer fluid.
Hitting the washer fluid button makes the turn signal relay click.
And reverse shorted something out.

The only extra on the gmt800 switch is an added wire and switch that goes up by the shifter handle, which can be deleted.

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[Eskimomann209]

I didn't know this was possible
What's the reason for the swap?

 

[eric_503]

Sorry on the delay, I have mine in and working. Have todo a write up.

Where I am in Canada there's an abundance of gmt800 trucks and very few gmt400's in the wreckers. It cost me a total of $10 for the GMT800 style instead of the $150+ for a new one here

 

[DRAGGIN95]

Good info!

 

[eric_503]

Still been swamped with work and more snow now.

To save myself time, I used my old wiper/cruise control part of the switch, they do unclip rather easy. (The box with the plug on the switch)
And inserted it on the new switch. The turn signal and hazard part of the multifunction switch seem to be identical pieces between the gmt400 and gmt800. You do have to cut all the wiring off the gmt800 switch, and use the old gmt400 harness and solder or crimp the wires together to the new gmt800 switch.

The colors will be different but #1 wire on the gmt400 harness goes to #1 wire on the gmt800 switch and so on. Most of the wires do match up in the same color , and only a few are different.