The trans light blinks on my trooper intermitently. I think it happens when it downshifts to first gear or when it hits a lower RPM. I cleaned the contacts in the neutral safety switch and added trans fluid. I can still manually shift
the trans. When I turn off the engine and on again the problem seem to go away.

I need suggestions from you guys to fix this problem..btw I am a newbie to this forum

there is a way to force the TCU to give up codes, just like the CEL.... man, I wish I remembered how to do it. I think it involves pulling out the transfer case shift boot and messing with one of the harness connectors under there... Anyone else remember?

Things to check:

1. your fluid... is it low? is it *any* color other than pink? Brown fluid means your shizz is burning, check for other problems, check for plugged or kinked cooler & lines, fluid leaks, etc. DO NOT OVERFILL THE 4L30E IN OLD TROOPERS!!!!! IT WILL BURP OUT THE FILL TUBE ONTO THE HOT EXHAUST MANIFOLD AND BURN YOUR RIDE TO THE GROUND yes, really. there was even a recall about that.

2. your temperature - is the trans getting way hot? do you feel heat radiating at your legs from the "hump" in your floor? are any of the wires that hug the transmission (look under the truck) melted? (yes, this can happen)

3. your shift lever position - does the little orange flag line up with the gear you're in exactly? do you have a body lift?

4. your fuses... check all the fuses under the hood, in particular the one for your reverse-lights AND the reverse lights themselves (yes, burned out reverse-lights or their fuse WILL throw a trans code)

5. wiring harnesses - check the ones on the passenger side for ugliness or corrosion. If you want to be thorough, unplug, clean, and apply electrical grease to all of the plugs there in that big wiring cluster behind the battery.

Yes overfilled it last week and it burp a significant amount of fluid..it stinks. The fluid level is correct now.

One of the exhaust pipe run directly under the transmission pan and pretty close to the neutral safety switch too. I ordered a heat wrapped yesterday hopefully it will come this weekend.

I will check the wiring harness thats the one that I havent check yet nor replacing the transmission filter and
fluid. I wonder if a defective shift solenoid is causing it too.

If you can remember how too give up the code please let me know

Thank you very much Shovel for your input.

Found a temporary solution to the problem. I noticed that the trans goes to limp mode downshifting from 2nd to 1st geat or 3rd to 2nd gear and when the rpm hits 1000. I basically adjusted the idling to between 1500 and 2000 rpm
so when I apply the brakes or when it downshifts the idling
will be above 1000 rpm. For now this temporary fix works for me.

Sounds as though your alternator is not putting out enough at the lower RPMs (that will cause the tranny to drop into limp home mode).

Check the output of your alternator at 1000 RPMS.

Thanks...I will try that tommorow

the alternator current is fine below 1000 rpm. I am now facing a blank wall again. I am now suspecting that its the shift solenoid but which one. Is it easy to replace?

I changed the shift solenooid on my escalade with 4l60e trans and its really easy. I am not familiar with the 4l30e. Help!!!

Does anybody know where the TCU is located on the 91 trooper
with Automatic transmission...Also can I easily access
the shift solenoids if I take the transmission fluid pan?

The TCU is mounted under the left dash on the drivers side.

The solinods are under the fwd pan of the Transmission.

Do you Need parts?

John

FWD pan, is that the small pan between the engine oil pan and the trasmission fluid pan?

Yes I will need parts...possible the 2-1 solenoid..