Blank transmissions display??

[summit]

Soo... I where the display where it tells you what gear the van is in has gone blank and when I move the shifter lever in to drive it moves freely down to drive, but it is only in first. Then when I try to put it back in park it will not go back.
I have no warning lights on!!! Eventually I have to jiggle it and pump the brake for it to go back into park again. Yet no matter what I am doing, there is no display of P R N D at all times now. Any suggestions would be greatly appreciated. Thanks Jimmy

 

[Nautamaran]

Are you able to scan the Transmission controller, Instrument cluster, or Shift module for fault codes or live data?
These communicate over the canbus to control and display the selected gear.
Any of them could be responsible...

-dave

 

[Cheyenne]

If you don't have immediate access to a suitable scanner then check the wiring plug onto the TCM in the drivers seat base for oil contamination. The trans fluid leaks past the 'O' ring on the plug on the trans and then wicks up the wiring until it reaches the TCM where it shorts out the tracks.

If you find oil in the TCM then others have successfully cleaned the module with electrical contact cleaner.

Keith.

 

[Axiom]

I think the big question here is what tells the instrument cluster what gear you're in. Is that the TCM or the gear shift module itself? To me since you can move the lever freely, I would either think the linkage came apart or the gear shifter thinks you're pressing the brake in no matter what hence why you can move it so freely.

 

[Nautamaran]

I agree: check the TCM connector and the physical shifter linkage.

The Shifter sends out “selector position” messages over the canbus, and physically moves the gear selector linkage on the transmission. The linkage moves the Park pawl, neutral switch, and primary valving, and provides a physical fail-safe to get back into neutral in case of an electrical failure.
The TCM receives and interprets these “selector position” messages and periodically broadcasts a canbus message containing the current selected gear, it’s target gear, and the actual engaged gear.
The IC watches for these TCM messages on the canbus and displays the current selected gear.

(Remember that when in a Rev/2nd-gear limp mode the TCM ignores the shifter being tapped left or right and the IC continues to show “D” because the taps are interpreted by the TCM, not the IC)

The Shifter receives an electrical signal from the brake pedal switch that energizes the Park lock solenoid and allows you to shift out of Park. This lock can also be manually released by inserting a rod/pencil/screwdriver through the flap next to the “D” on the shifter.

Since you can leave Park, your brake switch signal is reaching the shifter.
The sticky movement returning to park suggests a physical issue with the linkage?
The lack of IC gear indicator suggests an issue with the TCM’s canbus connection.
The IC’s canbus connection is probably okay if your other indicator lamps (SRS, ESP, etc) are being turned off. This occurs in response to messages from these other modules coming in over the same bus.

-dave

 

[Midwestdrifter]

The position potentiometer in the shifter could also have failed?

 

[marzbomber888]

Did you ever solve this?