Engine/Transmission (1994 - 1998) Electrical bug... Overdrive Off Randomly turns "on"

[Bobcat698]

98 Quad Cab Dually Auto.



While driving, the truck will randomly light up the "overdrive off" button on the dash and shift out of overdrive, seemingly just for fun.



Any idea what would cause this?



Thanks in advance!

 

[Howard Durand]

My 94 has done that a few times since it was new but very seldom. It about has to be a PCM thing. All the OD Off switch does when you press it is momentarily ground one of the pins in the PCM. Does the same thing when you press the button to re-engage OD. That pin has 9 volts on it so grounding it would drop the voltage to zero and toggle the circuit in the PCM.

It is possible that some electrical noise is being generated that could be filtered out.

Check with a dealer and find out if a re-flash of the PCM is possible or if they can determine if something is causing more than normal pulses and spikes in the 12 volt system.

 

[Shadrach]

Check out the "geashift control" - the expensive linkage bracket assy on the engine. When it goes it will shift in and out of OD irratically. You will have to go to Chrysler to get it. Shadrach

 

[SAndreasen]

my 95 did this alot and it was the trans temp sensor only about 60 bucks from dealer . i also had a full dtt trany and temp gauge and only got the transmission hot enuff one time for it to actualy kick out of overdrive .

 

[Howard Durand]

The "gearshift control" and temperature sensor may cause the OD to either not engage or unlock but I don't think either of those problems will turn on the "OD Off" light.

I am not sure the later models have the temperature sensor.

The times that this has happened to me, I had to poke the button to get it to go into OD.

 

[Ahopper]

mine has done this a couple of times. once i got the trannie too hot and the trans temp light came on and so did the od off light with the kick into thrid. the second time it did the same thing with the same lights but the trans wasnt hot. it ended up being my ground wire from my trans control from dtt was loose. so check all ground conections