Steve Collison

Yesterday, I wrote about how you can manually test your A604 transmission by engaging the solenoids directly – bypassing the transmission’s control module and possibly faulty wiring issues.

It is important to note that if your solenoid pack is bad, this test will fail. Here’s how my testing went:

Notes: I jacked up the van and put the front end on jack stands. I stuck bricks either side of the rear wheels and pushed on the emergency brake. I actually cut the solenoid connector end of the harness and wired my wires directly through that. I did resistance tests between wires 4-5, 4-6, 4-7 and 4-8 to make sure that I had connectivity with the solenoid pack.

I started the engine, and put the van into drive. It engaged nice and quickly, so I gave the engine a rev. My van shook like crazy. When looking beneath the van, I noticed I have a slightly bent drive shaft! But that’s a problem for another time, when I have the transmission repaired…

With the transmission now running, I started my test. First I engaged solenoids 7 and 8 – this should engage the clutch for the 1st gear. It didn’t. I had 1st gear before I started this test, so I was a little confused.

(I left it for a little at this point, and went and played with my old solenoid pack. I dismantled it and actually removed the four individual solenoids. I found that the solenoids made no noise (or basically did nothing) when I applied voltage to them directly. Interesting for sure.)

I went back to the vehicle and decided that I’d try to engage 4th gear. I engaged solenoids 5 and 6 as documented in the previous entry. The strangest thing happened, the vehicle started to slip and lost all speed. When I released the solenoids, it jumped back into 2nd gear.

Testing of these solenoids individually showed than solenoid 5 directly caused this and solenoid 6 actually did nothing. At this point, I’m starting to wonder whether THIS solenoid pack is actually any good. I bought it for $60 on eBay from a dealer that supposedly refurbishes and tests them.

I took the solenoid pack off the vehicle, and dismantled it. Solenoid 5 engages. Solenoid 6 and 7 make noise when you shake them up and down, but they don’t engage. Solenoid 8 is stuck and makes no noise when you shake it up and down.

I conclude from this that I have a bad ‘guaranteed working’ solenoid pack.

Friday will be the next day I can actually do anything. I’m going to go to the scrap yard and find myself another solenoid pack to test.

To note, when you don’t change your fluid it starts to gum up and this can cause solenoids to get plugged up. Therefore, this places even more importance on changing your fluid!

I have a hunch that the transmission is mechanically okay, given my lack of working solenoid packs. But only time and testing will tell. I am glad to say thought that my method of testing as shown in the previous entry officially works!