1995 C2500- Gear Indicator Alignment

[Urambo Tauro]

1995 GMC Sierra SL C2500, 4L60E, 295,000 miles

Hi guys, so the automatic transmission gear indicator under my speedometer has been acting a little goofy lately (well, it's actually been this way ever since I got the truck). This is the type with orange LED lamps underneath each letter/number, and the transmission was supposedly rebuilt by the previous owner.

What's happening is that the gear indicator sometimes indicates the wrong gear, and I am left having to ignore it and feel for the shifter detents instead. My muscle memory can deal with this just fine, but it's getting annoying seeing the wrong light on the indicator.

The lamp under P lights up when in Park, and I get the lamp for R when in Reverse as well. So that much is spot-on. But once I shift to the next detent (Neutral) the indicator for R remains lit, but the one for N stays dark. As I shift through the next detents, the indicator is off by one. In OD, I get the N light; in 3rd, I get the OD light; in 2nd, I get the 3; and in 1st, the 2 lamp is lit.

BUT as I go back up through the detents, it seems to realign. As I move the shifter from 1st to 2nd, the 2 lamp stays on. Shift into 3rd, and I get the 3, and all the other lamps up through P light up exactly the way they should.

So the alignment seems to partly off as I move the shifter "down" through the gears, but it seems to work just fine on the way back "up". Do I have a bad range sensor, or is this something that can be remedied by resetting the alignment?

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[east302]

Here are the diagnostics for a 1998 with the 4L60e, I'm going to guess that it'd be the same for your 95. Hope it helps...

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Connector C2 at transmission range switch:

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[Urambo Tauro]

Great diagrams! I'm going to go ahead and save those in case I ever need them.

But TBH, I'm pretty convinced that the problem at hand is mechanical in nature. Electricity is getting through to the correct spots, but only part of the time. I think that there might be some slop in the range sensor mechanism, but I'm not sure if I can adjust it out. Is there a method for adjusting it without using that "J 41364-A" tool?

 

[Urambo Tauro]

I had an assistant shift through the gears while I watched the movement from underneath. I think I saw a little bit of play between the manual shaft and the collar part of the switch that slides onto it...

As for trying to adjust it: It turns out that I can get a whole new switch for less than the cost of an alignment tool. And those new switches come with an alignment key for installation, so yeah maybe I'll just replace it.

 

[Urambo Tauro]

Bingo! A new switch fixed it. The inner collar fits much more tightly on the manual shaft, and the dashboard indicator now reads properly in all gears, no matter which direction the lever is moved. Even the "1" indicator lights up now.

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