Chrysler Dodge 42RE Governor Solenoid Problems.

The Chrysler, Dodge transmission series 42RE, 44RE, 46RE, 47RE (A500-ES) 1993 through 2003 are notorious for failing to start in low gear. The culprit is often the Governor Pressure Solenoid. The normal function of this solenoid is to generate a hydraulic pressure based on the road speed of the vehicle. The pressure should be low around 10 Psi at idle, and increase steadily with road speed, and throttle response to a high of 100 Psi.

As with earlier, hydraulic ( non electronic) transmissions, the governor pressure is used to move the shift spool valves in the transmission. When a valve is shuttled, the transmission fluid will be directed to a different circuit, causing the application and release of clutch elements. In simplifying the system, consider the 1-2 shift valve to have the weakest return spring. The weakest spring will compress first allowing the 1-2 shift to occur before the 2-3 shift, of which, the 2-3 shift valve has a relatively stronger spring. So the higher the Governor Solenoid pressure, the heavier spring it can compress. ( 1-2 valve moves before the 2-3 valve).

So what happens when you do not have first gear, and your Dodge Ram is trying to start off in second gear? Pretty simple huh? Yup, you guessed it, the Governor Solenoid pressure is to high, and has already moved the 1-2 valve into the 2nd gear position.

To understand why this happens, one must look into the design of the Governor solenoid. This solenoid is a proportional solenoid valve, which uses a tiny internal spool valve to allow the solenoid to give an output pressure that varies in proportion to the electrical current fed to the solenoid. The tiny spool is prone to getting plugged with metallic debris, which either causes it to stick, or eventually get worn out in its bore, allowing transmission fluid to leak by. In either case
the solenoid ends up putting out too much pressure, and hence the loss of low gear.

To make matters worse, the designers of this solenoid found a way to dramatically reduce the size and weight of this device as compared to other like products. Instead of using a large heavy copper coil, the designers used a small copper coil and an internal magnet within the Governor Solenoid. The combination of the small coil, and the magnet, produces the same amount of needed magnetic flux energy, as the larger copper coil used in like designed products. This reduced the overall product weight around 80 %, making the Chrysler Engineers very happy. (Lower weight =improved fuel economy). The downside is that magnets attract ferrous particles.
These little bits of steel that wear in the transmission get attracted right to the solenoid and end up plugging the spool valve, and or accelerating the wear of the tiny spool valve. Chrysler engineers even added a protective shroud around the solenoid to help minimize this occurrence.
But it's function is in my opinion, merely cosmetic.

So when you loose you 1-2 shift at somewhere between 60 & 100K miles, this is the most likely cause. Keeping your transmission fluid clean will help postpone the failure, but it will not prevent it. The solenoid is Mopar part number 4617210. It can be serviced fairly easily, but you will have to drop the transmission pan to get to it.

4L60E Trouble Installing Solenoids

Surprizing enough, once you think you have heard everything, something new comes along that makes you wonder should this person on the other end of the phone be allowed to work on a transmission. Part of the downside of offering technical assistance over the internet is that you get contacted by those who's little bit of knowledge has got them into big trouble.

During this more than hectic day, with 1 person in my office and another two waiting out in the hallway my phone was violently ringing, and refusing to wait for me to finish my conversation. With an apologetic gesture, I curtailed my conversation, and held my index finger up to those in the hallway to signify, please give me a minute. I slid away a mound of transmission parts, project books, and blueprints ( haven't been blue for 25 years) to get to the angry plastic box with the flashing red lights.

I gave my usual breif introduction and asked what i could do to help. The customer at the other end of the phone rattled off some part numbers of two solenoids he bought to repair his transmission. I confirmed the parts were made by my company, and asked what were his concerns. Expecting to hear of some bizzare service code, or malfunction that he had after he finished his repair job, I was dumbstruck when he said I can't find where to put them in the transmission. " I spent a good hour looking all around the transmission, cept in dem spots i can't see up top" He continued with: "So I took the transmission off of the engine and laid it on the ground so i could see the top side" "I think you-all put the wrong parts in dis box, cause i don't see nothin like this on my transmission"

Politely, I paused and informed the gentleman on the other end of the phone, that the solenoids fit inside the transmission. And you have to remove the transmission pan to get inside. With the pan removed, you can pull off the transmission filter, and you will see a total of six solenoids installed into the valve body. Two of these will match those you have in your hand. ( items A in the image below) I further explained the removal and re assmbly sequence, and suggested he may wish to refer his repair to a qualified transmission shop in his area.

For many shade tree mechanics, this is not a difficult repair, as for this guy, I hope he took his job to someone who knows the solenoids go inside the transmission!

Time to run, I have two people in the hallway waiting for some help.