RMK

I'm wondering if it is possible to test the lockup Solenoid with the tranny out of the car? Reason I'm asking is that I don't believe the TC has been locking. I checked the electrical connecter tonight and it was connected up alright. I'll be pulling the tranny to make way for the Pro-Built and wan't to try and fins out what is causing it not to lock.

Thanks

Robert

dankhound

To test the solenoid just apply voltage to the correct pins. You will be able to hear and feel the solenoid click.

five7kid

iTrader: (14)

It would be best to do more diagnostics before you pull the tranny. Try the ALDL manual lock-up first. If that works, then the ECM isn't doing its job for some reason. If it still doesn't, you have to verify power is getting to the tranny (turns out that was my problem). The power goes through the brake light switch first.

RMK

Thanks for the replies.

There are 3 wires going into that connecter, does anyone know which ones do what?

five7kid,

The tranny is still in the car at the moment. I tried the manual lockup with the ALDL a few nights ago and it made no difference. Where is the brake light switch located? I might try looking at that next.

Thanks again

RMK

I think I have found out what the wires are.

Dark green - top gear input signal
Purple - brake switch
Tan/black - TCC control

So am I right in thinking that if I climb under the car and put 12v through the purple wire the solonoid should click? I presume you can hear it clicking?

Still looking for the loaction of the brake switch though.

five7kid

iTrader: (14)

The ECM locks up the TCC by providing the ground for the circuit, not the power.

The brake switch is located on the brake pedal. Sticks to the rear, when the brake pedal moves the switch "breaks" the power circuit.

There is also a 4-3 normally-closed switch on the tranny valve body (inside the pan) in series with the power. It unlocks the TCC when the tranny shifts from 4th to 3rd.

RMK

So I can use my multimeter to check there is voltage accross the purple wire where it goes into the tranny. If there is voltage, then I can try touching the brake pedal to see if the circuit breaks. If it does break, the switch is good. If not, the switch is bad.

If I disconnect the switch so there is a break in the circuit, the converter should be locked unless there is a problem with the switch inside the pan, problem with the actual solenoid, or worst case, a problem with the converter itself?

Does the car need to be in gear when I carry out this test? Or can I just jack it up and leave it in park?

Thanks again

five7kid

iTrader: (14)

Not sure what you mean by that.

Not to check voltages or continuity. However, the clutch itself won't lock unles the tranny is in 2nd gear because no fluid goes to the clutch until then.

RMK

I just tested the switch. I left the connecter in the switch and checked the voltage accross the purple wire. When the brake pedal was pressed there was voltage (about 18V with the car running) from the purple wire. When I released the brake pedal the voltage dropped to 0.4V.

So the brake switch is not the problem then.

What would you suggest trying next? The purple wire going into the tranny?

Thanks again.

five7kid

iTrader: (14)

Make sure the power is getting down to the tranny. Like I said, that was my problem (never figured out exactly why, just ran parallel copper).

Then, it's probably time to pull the pan.

RMK

I'll try and crawl under tomorrow after work. I suppose I could just pull the connecter from the tranny and check the end terminal at that point?

Sorry about what must seem like stupid questions, but this is my first time of chasing electrical gremlins like this.

Many thanks

RMK

I just went out with a friend and started to work with the connecter that goes into the trany.

We pulled the connector out from the transmission and checked the purple wire.

When the pedal was not pressed the voltage accross the purple wire was 0V. We then pressed the brake pedal and there was no change in voltage, still 0V were showing on the meter.

We then checked the voltage accross the brake switch with the connecter from the tranny disconected and the same scenario appeared to happen with the purple wire and the brake switch. Would this be normal or should the brake switch still have operated properly with the connecter remover from the tranny?

I'm wondering if I have to test this with the connecter plugged into the tranny and poke the multimeter probe into the purple wire with it connected up?

Incidently, the other 2 wires going into the tranny, on that same connecter, showed voltage regardless of whether or not the brake pedal was pressed or not.

Suggestions and advice are needed please.

Thanks

Robert

five7kid

iTrader: (14)

It's been a couple of years, so I had to go out to the parking lot for a refresher on all the wire colors. Wouldn't you know, my supervisor would chose that time for a smoke break...

You should be checking voltage with the positive meter lead on the circuit being tested, and the negative to chassis ground. Is that what you're doing?

The 4th gear indicator is a high-impedance 12 VDC going to the normally-open single-pole switch on the valve body. When 4th gear is engaged, the switch grounds the wire, which drops that line to ground potential; this voltage drop is sensed by the ECM and then it does things that it will only allow in 4th gear (for some models, that includes locking the TCC). So, with the trans connector unplugged, it should be 12 VDC to ground with the ignition switch on.

The purple is the TCC power from the brake switch. It should have power with the ignition switch on and brake off. It shouldn't be affected by being plugged into the tranny or not. The TCC control should be zero volts to ground with the switch on and engine not running.

I finally figured it all out with the pan off and the connector connected - plus a healthy helping of help from people on this site.

BTW, there are two connectors on the brake light switch, one for the brake lights, one for the TCC power. The brake lights are blue wire, IIRC (didn't check that in the parking lot - have to drop a panel).

RMK

Quote:

You should be checking voltage with the positive meter lead on the circuit being tested, and the negative to chassis ground. Is that what you're doing?

Yes, that is have been doing.

Quote:

The 4th gear indicator is a high-impedance 12 VDC going to the normally-open single-pole switch on the valve body. When 4th gear is engaged, the switch grounds the wire, which drops that line to ground potential; this voltage drop is sensed by the ECM and then it does things that it will only allow in 4th gear (for some models, that includes locking the TCC). So, with the trans connector unplugged, it should be 12 VDC to ground with the ignition switch on.

That is exaclty what appears to be happening with the dark green - top gear input signal wire!

Quote:

The purple is the TCC power from the brake switch. It should have power with the ignition switch on and brake off. It shouldn't be affected by being plugged into the tranny or not. The TCC control should be zero volts to ground with the switch on and engine not running.

When I pressed the pedal there was voltage accross the purple wire. From what you are saying it should be the opposite? Voltage when the pedal is not pressed, and the voltage should drop whe the pedal is then pressed. That's interesting.

Quote:

BTW, there are two connectors on the brake light switch, one for the brake lights, one for the TCC power. The brake lights are blue wire, IIRC

I'll double check this. I believe there were 2 connectors on the brake switch itself. 1 with only 2 wires and another with about 4 or so.

Quote:

I finally figured it all out with the pan off and the connector connected - plus a healthy helping of help from people on this site.

I am now starting to believe that this is the only way to solve this problem. I've never removed the pan before but I'll remove the pan on Saturday when it's light outside and I'll have all day to have a good proper look at what's going on in there. I'll report back on Saturday.

I'll try the manual lockup with the ALDL again. I tried it with a paperclip the last time as it was all I had to hand. I'll try some proper wire and ensure the connections are good.

Thanks again

Robert