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View Full Version : 4L80E Hard 1-2 Shift, '91 R2500



Duncan Sterling
12-13-2004, 11:31
Greetings,

I've got a new (to me) R2500 with a 6.2 and 4L80E, 116k on the clock.

The last time the vehicle was driven (in October), it shifted normally between 1st and 4th (OD) without any issues, and no known problems before that either.

Now, I just taken it out for a local drive and I'm getting hard shifts from 1-2, though everything else seems OK.

Fluid is not new, but looks and smells OK, the truck has mostly sat for the past 2 years and has 116k on the clock.

Only real difference in driving conditions is that it was in the 70's in October and the 40's now.

Is this most likely to be

1) A bad TCC valve?

2) A bad 1-2 shift solenoid ?

3) Loose wires/harness (the trans wiring and shift linkage had been disconnected and has only recently been reconnected)?

4) Temperature related?

5) A rebuild waiting to happen ?

TIA for any and all responses/pointers/info...

--Duncan

diesel65
12-13-2004, 12:31
Do a code check and see if you have code #21, if so replace the TPS.
You will need a scanner to set the TPS voltage or you might get away back probing the connector and set it for about .70 volts at idle

C.K. Piquup
12-16-2004, 15:25
When was it last back-flushed?Ask the PO.