I had the 700r4 rebuilt this spring and the car was running fine. Then one day the car started to act up and would hardly run. No power and kept on stalling at stops. Service Engine Soon light would come on and off intermittently.) I thought it was the injectors. My friend had his 89 torn apart and called me and was offering his MAF (Mass Air Flow) sensor to use. He suggested I check the ECM for stored codes. When I was going to install the MAF, I used the paper clip method to check the ECM for codes. Because I was in a hurry, I connected ALDL E and F instead of A and B. The Service Engine Soon light would not flash. So I disconnected the battery and removed the current MAF and hooked up my friends MAF. I took the car our for a drive and it ran fine. Did notice it did seem sluggish while accelerating on the hi-way around 40 to 45 MPH. Since then I bought a new MAF and the engine runs fine. While in town, Auto Trans in OD, I am assuming the TCC locks at about 35MPH and any little throttle increase causes the car to chug and I immediately shift it into D instead of OD. My question to members of the forum. Did I damage the TCC solenoid or the ECM when I connected ALDL terminals E and F instead of A and B? When I did this, the key was turned to ON but did not try to start the engine. I was going to try going thru the FSM TCC diagnostic chart in section 6E3-C8. Any suggestions?

 

The tcc solenoid in the tranny can't be hurt. 12 volts, off or on. The ecm might be a different story.

 

you should be NOWHERE near OD below 55 mph...jeeze...OD @ 1100 rpm? of course its chugging...or whats more commonly called "bogging" the motor down. That'll kill it.You can't do OD IMO below 15-1600 rpm or until the motor is well into the power band. At 35 mph thats just off ilde in 4th gear(OD). Horrible stress for the power train.

I'd strongly suggest that you seek TV cable adjustment and get a FSM and learn how the system functions.
You CAN drive around all day in OD as long as its adjusted right. That will allow a looser operation of the TCC and give it a softer feel. Drive city in 3rd and the TCC will lock in sooner and hold that until min rpm/speed OR brakes are applied.

 

I keep my trans in D instead of OD unless I'm going over 50 MPH (3.07 rear ratio). It prevents the bogging and shifting back and forth between D and OD.

The ECM uses the same parameter to turn on the TCC solenoid as it does to turn on the shift light, so the TCC will lock at the same time the shift light comes on. Mine locks at 42 MPH in D.

 

Shift light? Is this the light on the Instrument panel gauges that says 1st to 4th shift. I thought it might me for 6 speed manual setups. I have never seen the light come on. Is the light bulb bad or the ECM not sending the signal to turn it on? Reading thru the owners manual, it says OD is for normal driving and D is for extra performance. (Like going up hills.) I have seen several threads on this subject. Some say that you should be able to put the tranny gear selector in OD and just drive and others say that you should be above a certain MPH or RPM before putting it into OD. The car was running fine in OD before I inadvertently connected the E and F connectors (instead of A and B) on the ALDL to check for stored codes and replaced the MAF.

 

Well the 'F' pin is the TCC lockup and has 12 volts.

The 'E' pin is the 'data' line and is from 2 to 5 volts..

So could you have damaged it?

Possibly. But the data line is an 'output' from the ECM and is generally an op-to-isolated connection.

Even if you apply 12 volt directly to it, it would more than likely fry the op-to-isolator and not damage the rest of the ECM.

But, without a schematic of the ECM, I'm just assuming that the output buffer is isolated that way.

 

The digi dash has an "UpShift" lite that will illuminate if your driving in lower gears for extended periods. And Yes it does work for automatics.