Engine/Transmission (1998.5 - 2002) transmission won't shift

[cerberusiam]

Before considering replacing OD solenoid and wiring harness, wire a mystery switch into the OD circuit and verify that mechanically things are functioning. Seldom is the solenoid or harness a problem, it is almost always an electrical glitch somewhere as OD is purely under computer control.



Validating mechanical operation will save you headaches and $$.



Typically intermittent OD can be traced back to gov pressure transducer and solenoid and\or the output shaft speed sensor, or, connection problems. Change out those 3 and go from that point.

 

[JLandry]

Greg,

Another thing you might try first before replacing any solenoids or sensors is to remove, clean (with contact cleaner) the wiring harness connector which is located on the driver's side of the transmission just behind the shift lever. This is the wiring that connects to the sensors and solenoids inside the transmission. The specific connector I'm referring to is on top of the transmission body, not on the side like the neutral safety switch. It's the one labeled "solenoid case connector" in the picture below.

Maybe there's a little corrosion causing an intermittent connection somewhere.

#ad

 

[Grmoore1964]

Thanks for the great info guys. I will get underneath and clean out the contacts. Maybe I can get lucky that way.



The problem is intermittent - but it works the way it should often enough that I believe that mechanically there isn't anything wrong. I am pretty convinced it is a solenoid or wiring problem. Either way, parts are already on order and it looks like I have a date with some ATF in the face next week.....



I'm tired of being under this thing - I just rebuilt the vacuum pump and I'm still picking grit out of my eyes and teeth... .



Thanks guys -



Greg

 

[cerberusiam]

The problem is intermittent - but it works the way it should often enough that I believe that mechanically there isn't anything wrong. I am pretty convinced it is a solenoid or wiring problem.

Those 2 concepts are really mutually exclusive. If it works most of the time it is not mechanical it is likely computer related. Now the electrical side of it could be a loose connection causing the PCM to just not demand OD.



Thats why I suggested a switch to validate operation. If it goes into OD every time you engage the switch its not the solenoids or wiring, its the PCM not doing its job. With a lighted switch you can tag the switch light into the circuit to tell if the PCM is grounding the circuit when it is supposed to.

 

[Grmoore1964]

I understand what you are saying now. Where would you wire the switch? Are you thinking a permanent switch or just for testing?

Thanks -

Greg

 

[cerberusiam]

Just for testing.



Pin #6 of the trans control harness is the OD sense circuit IIRC. Scotchlok an 18 g wire to it, run the wire to the light circuit of a SPST lighted switch, run the ground side of the switch to a 1/2 watt 33 ohm resistor then to a chassis ground. You could use just an LED inline somewhere also.



When the switch is engaged the circuit will over ride PCM control and ground the OD solemnoid circuit to engage OD. If the PCM is not demanding OD the light should illuminate as the resisted ground takes effect. When the PCM grounds the circuit power will flow the easiest route which is non-resisted and back thru the PCM. At the point the PCM takes over the circuit the light should go out as load has been diverted.



By watching the ligh you can tell if you are over riding the PCM and when the PCM is demanding OD. That will tell you if the PCM is just not demanding OD whne it should or if there is a failure in the circuits that is intermittent.



The 2nd gens aren't as managed I don't think. On a 3rd gen if you have an issue in a circuit for the solenoids it will throw codes and go into limp mode. All the circuits are monitord for resistance constantly. Tougher to track as you way have to ohm out the harness to find a scuffed wire or bad connection.

 

[Grmoore1964]

Well, an update.....

I fixed the transmission by trading it and another vehicle in on a 2012 Crew Cab 3500 SRW. Love the new truck!

Thanks for all the help and advice - I'm shipping the parts I ordered back and will now be hanging out on the 4th Gen forums!

Greg

 

[JLandry]

I fixed the transmission by trading it...

That's definitely one way to fix it!



John L.

 

[Grmoore1964]

It was definitely the most expensive way to fix it, but it worked! I've actually been thinking about upgrading for a while, and was offered a good enough deal that I just went for it.

Thanks again!

Greg