Seriously delayed 1st-2nd shift in low range only (1 Viewer)

[bmegdal]

'97 with pin 7 mod and CDL switch.

Had it offroad last weekend, and when in low range the 1st-2nd shift sometimes didn't happen until 4K RPM.

I had no time to dig into it this week so I had a local well-regarded transmission shop take a look. They confirmed the problem, but claim the transmission itself is fine, and the problem is "an electrical one", specifically with the signal from the transfer case to the ECU.

So before I dig out the FSM and start checking wiring I thought I would ask if anyone has seen this before. I know about the wires from the xfer case to the ECU that control center-diff lock and change the shift points, but this is more than a minor change in shift point.

Thanks

 

[landcrshr]

Seems pretty normal to me.

You can keep the 2nd start button on and manually shift between 1st and 2nd.

 

[bmegdal]

Definitely not normal -- actually went as high as 5K RPM. I have been driving this truck for >10 years and this is new.

 

[landcrshr]

The only wire to the ECU is from the 4LO position switch, It's the same wire as the pin-7 wire.

 

[bmegdal]

The only wire to the ECU is from the 4LO position switch, It's the same wire as the pin-7 wire.

Thanks for your help. Haven't gotten home to look at the FSM yet. So I'm not sure what the cause could be....

 

[rockstate45]

Have you ever been in 4lo before?

Depending on the way you're driving it, it doesn't seem completely out of reason that it'd do that.

 

[bmegdal]

Have you ever been in 4lo before?

Depending on the way you're driving it, it doesn't seem completely out of reason that it'd do that.

I've been driving it offroad in 4WD for years, and it has never behaved like this.

Thanks

- Barry

 

[inkpot]

Don't have the POWER button turned on?

 

[PBARDIS]

I'm keeping my fingers crossed for feedback on this. My 97 LX has the same problem. I have read some stuff on the shift solenoids, thinking this might be the problem. But have yet to diagnose it for sure. Please let us know what you find out.