Shift controller on WTEC3 showing -\-

[firebuilder06]

Check trans light is on, shift controller showing -\-, no start.
Issue happened just recently after having a check trans light and only have up to 5th gear. Ended up having no gears one day. Dug into WTEC3 diagnostic troubleshooting manual to find bad ECU. Replaced had no issues. Drove it a few times with no problems. Last time to drive it heading home the check trans light came on and only could go 40mph after a stop sign. Been digging to see if there is a short somewhere or if new ECU is bad. Troubleshooting manual shows -/- instead of -\- on selector switch. Any ideas?

 

[Ronmar]

Codes stored?

 

[firebuilder06]

-\- is the only thing that will display on the selector.

 

[MrMikey4026]

Known in the trade as a cat's eye. Power failure or low voltage to the transmission.
There are two circuits, constant power and keyed power. You will find an issue most likely in the constant power circuit.
Or a failed TCU, but not as likely as a battery or wiring problem.

 

[Mullaney]

-\- is the only thing that will display on the selector.

.
Clean the battery connections and charge and verify battery voltage.
Second thing is to look under the spare tire and (with the batteries disconnected) CLEAN the reverse polarity box that lives there. Clean it good and use Anti-Oxidation paste on the cleaned parts. The wires and the terminals.

Then, let's see what happens.

 

[Ronmar]

Ign is still cb79, but Iam not recalling where batt power to the trans controller feeds from on the A1.

 

[Ronmar]

On the A1 24V battery power is fed to the WTEC III controller by CB43

On the A0 12V battery power is fed to the VIM and WTEC II TCU via CB35.

On both models CB79 provides the 24V switched ignition power.

What year is this truck?