NO TCC lock up.. internal ?

[williamsGN]

ECM fuse is ok, 12v down purple connector - cuts off with brake pedal. Power across A to F on ADLD. I can hear the solenoid engage when I apply ground to the tan wire on the connector.
Continuity from A7 to tan wire on trans connector. ECM or internal trans problem ? Trans was just rebuilt 400 miles ago and TC was locking up fine until today.

Thanks

 

[silentbutdeadly]

Lonnie had a good write up on a scenario that covers this issue on his website. Have you tried to force it into lockup by using a check ball in the switch?

 

[williamsGN]

Have to check Lonnie's.

I assume if I hear the solenoid activate when grounded, it's not the problem ?

 

[silentbutdeadly]

Have to check Lonnie's. Not sure I follow on check ball in the switch ?

drop the trans pan, remove the lock up solenoid, put a check ball in the opening of end of solenoid that goes into valve body, install solenoid, install trans pan, start car and when car shifts into 2nd, lockup should happen immediately, if not then its the solenoid. I meant solenoid not switch, sorry.

 

[williamsGN]

If I jump the A and F with a paperclip and the TCC locks up I guess I have an ECM/switch problem. If it doesn't lock up then it is something in the trans. Would this be correct ?

 

[silentbutdeadly]

yes that sounds correct. does the converter lock up on its own while driving? only when forced via switch? neither?

 

[silentbutdeadly]

someone can correct me if I am wrong but if the ecm isnt seeing lockup then the pressure switches could be bad also. You can verify this using something like direct scan if you have that.

 

[williamsGN]

Not locking up, noted the RPMs a bit high and tried the tapping the brake trick which usually brings up the RPM about two hundred and drops it right back down. Didn't do that today.

Don't have direct scan, anyone know of another way to verify what the ECM is doing ?

 

[RmvBfrFlght]

Not locking up, noted the RPMs a bit high and tried the tapping the brake trick which usually brings up the RPM about two hundred and drops it right back down. Didn't do that today.

Don't have direct scan, anyone know of another way to verify what the ECM is doing ?

Connect a DVM measuring DC volts to pin F on the ALDL connector (same wire as A7 on the ECM). Key-on, engine-off, meter should read about 12 volts. Depress the brake pedal and the voltage will float around (due to it being an open circuit).

With the engine running and the car being driven the meter will read about 12 volts until the ECM commands lockup. At that point, if the ECM is working OK, the voltage will go to below a 1/2 volt (0.5 V). And the TCC should lock up.

Can also ground pin F of the ALDL to force lock up while moving down the road, such as you did in the original testing. This won't hurt the ECM.

If that locks it up and the ECM won't pull that line to ground (< .5V), there are a number of reasons. If the VSS input to the ECM is bad, it won't command lockup. Doesn't think that the car is moving.

It may also be that the q-driver in the ECM is bad. They usually show physical damage when they go out. Need to disassemble the ECM to check them. They are located on the lower board near the harness connectors.

If one is bad, be sure to check all relays and solenoids before replacing the ECM. Since one is likely shorted which fried the q-driver.

RemoveBeforeFlight

 

[williamsGN]

Took a test light and verified the ECM is sending a grounding signal to the tan wire. Grounded the same wire and can hear the solenoid engaging. Two questions:

Can the solenoid be defective even if I hear it engaging, I'm guessing so due to the check ball test mentioned above.

If not that, can I check anything else in the trans. With it being a fresh build I'm thinking that might be the issue.

 

[SSedan64]

Yes, the Solenoid can fail electrically or hydraulically.