Ok here is the deal. I grounded terminal F in ALDL with test light and after 3rd gear engages the light comes on. GM service manual says this is to test the electrical components to engage TCC. Suspected bad TCC selenoid. I bought a new one from GM dealer and replaced it yesterday, still no lockup. Could it be the converter is bad or do I need to replace the 3rd gear switch first?

quote Originally posted by vEnOm: Ok here is the deal. I grounded terminal F in ALDL with test light and after 3rd gear engages the light comes on. GM service manual says this is to test the electrical components to engage TCC. Suspected bad TCC selenoid. I bought a new one from GM dealer and replaced it yesterday, still no lockup. Could it be the converter is bad or do I need to replace the 3rd gear switch first?

IIRC the ECM grounds the TCC if: Above 32? MPH, Brake switch off, Closed loop, 3rd gear switch applied, and steady throttle. So either brake switch, 3rd gear switch, or the wiring to the TCC connector on the tranny.........Paul

If the light is going on (12V at the test terminal), then the 3rd gear switch is working. Does the light ever go out while in 3rd gear? Because if the light never goes out, then the ECM is never grounding the wire to switch the TCC on.

Edit: Voltage passes through the brake switch and 3rd gear switch to get to terminal F of the ALDL connector, so if there is voltage there, then they are not the reason the TCC won't engage.

[This message has been edited by Steve Normington (edited 07-01-2004).]

The light only goes out when the brake is applied or if I release the gas pedal. I hope is not the converter I just finished this car. I have driven it for only 400 miles doing the brake-in to the engine.

Thanks for your help.

I had the same problem. Per Ogre's advice, I unplugged the electrical plug going into the tranny and simply plugged it back in. My problem was cured....just a poor connection.

Glad I took his advise, the most obvious is usually the problem

Dave

I replaced my TC solenoid after doing the electrical check and still had to go back and replace the third gear switch as it was bad also.

I now have lockup that works great, I had been told to do the switch when I did the solenoid but I thought, how often could a switch go bad, Doh!

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Where will the road take you today?

If the light is on then all the electrical is fine....

As noted above power flow is from the brake switch, thru the transmission parts, to terminal F and the ECM.

The light never shuts off so that usually means either the ECM is not commanding lockup or the ECM lockup circuit is bad. (Bad could be a damaged wire/plug or the ECM itself.) An ECM scanner will tell you which one it is.

This assumes you even have the right chip in the ECM. If you have a manual transmission chip in there then the lockup will never work right.

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The only thing George Orwell got wrong was the year.

The Ogre's Fiero Cave (It's also at the top of every forum page...)

The lockup was working before I rebuilt the engine and tranny, but maybe something is not right in the connections. I will borrow an ECM scanner to check everything. Anyway I have a spare ECM, I will check everything before I go nutz and buy a torque converter.

Thanks to all, I will keep you posted if I find anything.

Buying a TC won't help you based on what you already posted. It isn't anything wrong in the transmission at all according to your previous posts.

The light must go out when the ECM commands lock. If the light isn't going off of at least dimming way down then either you are in the wrong ECM terminal or the ECM isn't telling the TC to lock.

read the electrical section in my cave and make certain you are in the correct ECM terminal. The ALDL connector can be mounted two ways.

You can manually force a lock by grounding the TC test terminal. Do this only for testing! Make sure you are cruising at a fairly steady speed in third gear when you do the test. If the manual lock works then there are NO problems in the transmission. If the manual lock fails there are posible electrical problems in the circuit what could be inside or outside the transmission. I doubt you have any actual TC or hydraulic problems beyond the solenoid and 3G switch.

Ok. I did the whole test again and found out I wasn't waiting enough. With a test light connected to terminal F and ground, light is on after 3rd gear applies then with a steady speed the light goes out but no lockup. I haven't done the manual lockup test, but will do after I get out of work.

Does your cruise work? My '88 had a bad connection between the speedometer panel and the ECM. When it was repaired, the cruise and the TC lockup both began to work properly.

This one doesn't have cruise. Still at work, as soon as I get out I will make the manual lockup test.

At that point, it could be the TC but don't count on it....

As I remember, the TC locks when the solinoid opens a valve and bleeds pressure from the TC lockup passage. If the bleed passage or the valve is blocked with dirt etc then the clutch won't work.

Thanks a lot ogre! + For you. If I have to drop the cradle I will send the tranny and converter to DreXter's brother in law who owns a tranny shop to check on both things. But at this point I'm thinking for an AOD conversion, reading your info at the cave made me lean towards it.