ASE doc

Does anyone have the wiring diagram for the TCC control add on for the gen 6 ACCEL DFI? I am trying to trace down my TCC inop. Before I pull the pan to check the 4th gear pressure switch, I want to be sure of how the system operates.

ASE doc

I'm on track to figuring this out. I isolated all the circuits to the TCC case connector and verified that pin A goes to terminal 87 of the TCC relay in the ECM harness(+12v TCC solenoid power when relay is energized). Pin B goes to the ECM pin A6 and is obviously 4th gear switch input. Pin D is chassis ground. The relay has battery power to terminal 30 at all times and ignition power to terminal 86 with key on. Terminal 85 of the relay is obviously low relay control from ECM pin B4. Now I need to verify whether the ECM is looking for a ground signal on pin A6 in order to energize the relay. I will most certainly end up dropping the pan to verify correct wiring before I have this figured out. Just need to be sure that I know what I'm looking at before I go there. I may have just connected the solenoid and/or pressure switch backward which might explain the inop TCC.

ASE doc

This morning, as the weather is finally decent, I hooked up my logic probe to the TCC relay in the ACCEL DFI 6 harness and monitored voltage while driving. Found out that, for one thing, I had the minimum TCC thottle position set too high. At 10% throttle, even at 55mph, the car is pulling too hard to have the TCC engaged, at least in my opinion. I set it down to 5% and found that the TCC relay is activated in every gear as long as the throttle is above 5% and the revs are above the minimum of 1,200rpm.

This means that either the 4th gear switch is providing the ECM with the signal it needs to activate the TCC, even when the trans isn't in 4th gear, or that the ECM doesn't need 4th gear switch input to activate the relay. With the relay activated, there is still no TCC lockup, which means that either the brand new TCC solenoid I just installed is no good, there is a hydraulic issue in the trans affecting pressure to the TCC, or there is a grounding issue to the TCC solenoid. I am leaning towards there being a grounding issue.

My next move will be to perform a voltage drop test across the ground circuit to the TCC solenoid. In this set up, the ground is external rather than the solenoid being grounded to the trans case. I'm thinking that this isn't the best way to have it set up. I need to be sure though that however I wire this, I only have converter lock up in 4th gear and not in every gear, as there would be if I just wired the TCC solenoid to case ground right now.

I monitored the signal on the circuit from the 4th gear switch to the ECM and it had .8 volts in all gears but 4th then dropped to .4 volts in 4th gear. I'm thinking that the ECM is looking for ground on that circuit when in 4th gear and that the range of .8 to .4 is close enough to ground that the ECM is commanding TCC in all gears. I'm going to disconnect this circuit from the ECM and see if the TCC relay doesn't activate with the circuit open. That will tell me that I need to focus my attention on the 4th gear switch and/or wiring, and the TCC solenoid ground.

Pat Hall

iTrader: (31)

Isn't it fun figuring out TCC issues? Lol. If all else fails, you can purchase a 4th gear only TCC lockup kit on Ebay for dirt cheap. They come with a one blade case plug, a pressure switch for the valve body, and some wiring. Just thought I'd suggest it if you end up wanting a simple, cheap solution.

hotrodgss1

Hate to revive such an old thread but I'm wondering if ASE doc ever figured it out? I'm having the same issue with the exact same setup; Accel Gen 6 ECM using pins A6 & B4 to control the tcc lock up on a 700R4. The only difference is my setup doesn't have a relay... keyed power is wired directly to the positive side of the tcc solenoid and the ground wire from the tcc solenoid is wired directly to pin B4 of the ECM. From everything I've read, this is incorrect and I need to wire up to a relay. That being said, it still works.

Using a test light connected between pin B4 and the tcc solenoid ground wire, I discovered that the light will STAY ON while in 4th gear if I disconnect the wire to pin A6. When A6 is connected, the light will TURN OFF when 4th gear engages. Since I'm using a NORMALLY OPEN 4th gear pressure switch, I'm assuming that the ECM is ENGAGING the tcc solenoid when it senses NO GROUND and DISENGAGING it when it senses a GROUND. I'm going to try directly grounding pin A6 of the ECM to see if my test light (which is still connected between pin B4 and the tcc solenoid ground) will light up. If it doesn't light up, then I'll simply need to replace my normally open, single pole 4th gear pressure switch with a NORMALLY CLOSED single pole one so that it only engages the tcc in 4th gear. If the light stays on anyway, I'll have to figure out how to rewire everything.