This is embarassing to admit but when I dropped the pan to change the tcc solenoid, I noticed I crossed the tcc wires. I looked at it with embarrassment and disappointment when I saw the wires crossed. So I proceeded to take out the solenoid and hook up the new one the right way. So maybe I did short something out? Could something that stupid ruin the tcc circuit?
Weird hesitation in overdrive
- Thread starter Qwkspool
- Start date
This is embarassing to admit but when I dropped the pan to change the tcc solenoid, I noticed I crossed the tcc wires. I looked at it with embarrassment and disappointment when I saw the wires crossed. So I proceeded to take out the solenoid and hook up the new one the right way. So maybe I did short something out? Could something that stupid ruin the tcc circuit?
Hey Rick, I'm still having a problem figuring this out. I have a ecm on the way so I wanted to check some wiring. I have 12 volts at the brake switch and it goes to 0 when the brake pedal is pushed. On the 4 prong harness, I have power to all pins on the wire harness except for pin D. When I give power to pin A and try to ground pin D to the tranny, nothing happens. I also do not have power at the aldl connector. So I dropped the pan again and checked for pinched wires. I didn't see anything so I took the tcc solenoid out. With it out if I connect the power and ground, I do not hear a click at all. Does that mean it's bad? And even if that's the case, that means that something must be messed up with the wiring outside the transmission. It only occurred after I installed a shift kit and wired the tcc solenoid up backwards (i bought a new one to replace). So I'm not sure what else because nothing else was touched.
- Joined
- Feb 18, 2006
The ecm grounds pin D to activate the solenoid.
Pins B and C are the signals for 3rd and 4th gear. There only function is to report to the ecm.
When the ground is lifted on pin B it signals the ECM that the trans is in 4th gear.
Likewise for pin C and 3rd gear.
Not sure if the solenoid will click on a bench test. You would think that it would do something.
Diagram below may help.
Rick
Pins B and C are the signals for 3rd and 4th gear. There only function is to report to the ecm.
When the ground is lifted on pin B it signals the ECM that the trans is in 4th gear.
Likewise for pin C and 3rd gear.
Not sure if the solenoid will click on a bench test. You would think that it would do something.
Diagram below may help.
Rick
Thanks for the reply. So by looking at the diagram the zero volts at the F port of the aldl could be ecu related? Not sure why else I woundnt have 12 volts there by looking at the diagram. I took out the ecu and nothing looked burnt or smelled funny. I have two tcc's that do nothing when I try to bench test them but the original factory one clicks when I bench test it. But that one stuck so I had to replace it.
- Joined
- Feb 18, 2006
Pin F is the negative side of the solenoid coil. It does not have 12v. Grounding pin F on the ALDL will activate the solenoid.
Last edited:
I'm a little confused now. I thought pin a on the aldl was the ground and pin F had 12 volts. That way when you jump the two, it completes the circuit and activates the tcc. I thought one of the puns was supposed to have 12 volts with key on. Neither of them do for me so I wasn't sure if that was a problem.
- Joined
- Feb 18, 2006
If you jump power to ground that's a dead short. When you jump A to F you are supplying the ground to the solenoid.
Power is supplied through pin A of the trans plug.
Power is supplied through pin A of the trans plug.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
Note in the diagram Rick posted the diode across the TCC coil. When power to the solenoid is reversed, that diode fuses. This renders the solenoid null & void.
Measure the resistance of the solenoid coil, a good one measures about 22 ohms.
RemoveBeforeFlight
Measure the resistance of the solenoid coil, a good one measures about 22 ohms.
RemoveBeforeFlight
Ok that makes sense now. So jumping pin a and f just completes the ground. So pin f would not have 12 volts. I have a mutimedia so i will check the ohms of the solenoid. Does anyone know if it should click when bench tested with a 12 volt battery? I guess it has to be the ecm at this point. But is weird because the ecm and car only acts up when the lockup is supposed to happen.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
With everything installed and connected, key-on, engine-off, ALDL pin F should have +12 volts on it. If not then there is an issue. Unplug the ECM and check it again. If now there is +12 volts the quad-driver in the ECM is bad.
Yes, it should click.
That is because the ECM is/was trying to ground +12 volts, the diode is fused (shorted) due to the reverse polarity.
RemoveBeforeFlight
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
No codes in the stock ECMs for bad quad-drivers. Also, I tested a 700R4 TCC solenoid on the bench, upon applying power it gave a loud click. But removal of power and re-applying gave nothing. Still ohm'd OK, but not sure why it only clicked the first time. Maybe that isn't a valid test, or residual magnetism needs to fade, I dunno'.
RemoveBeforeFlight
RemoveBeforeFlight
This is driving me nuts. Here's where im at now. I don't have 12 volts at pin F with key on, engine off. Even if I unplug the ecu, still no power at pin F. I do have power at pin A on the transmission plug and on the purple wire at the brake switch? I took off the aldl and nothing looks wrong with it. On a side note, on both of the aftermarket TCC's the ohms measure 20.8 but does not do anything on a bench test. The original TCC that I removed years ago because it was sticking measures 25 ohms and clicks every time I touch the wires to the battery. So I'm not sure what to make of the TCC if they are bad or not. I thoughts they dre so I bought another one. I will have overstock on these soon lol. And obviously I still have a wiring problem because I do not have 12 volts at pin F. Not sure where to go from here. I wish it wasn't bad to drive around with the transmission plug detached because it performs great otherwise, besides the poor mpg. Oh yea, I even tried the other ecm and no change with the pin F volts.
Update; I must be electrical illiterate. I didn't realize you must have a tcc solenoid hooked up to get 12volts at pin F. I have my transmission pan dropped while I am trying to diagnose this problem. No matter which tcc I have hooked up, I have 12 volts at pin f. But when I ground pin f only the old tcc clicks. So I don't want to put everything back together if I have bad tcc's. Still doesn't explain why I was having my original problem with the ecm freaking out.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
It was because the diode across the solenoid coil was being forward biased. IOW, it was a near direct short across the coil.
RemoveBeforeFlight
So do you think I should wait till the new tcc comes in even though I have two here that shows over 20 ohms for resistance, but still don't click when bench tested? I was going to install the new ecm anyway just in case. I would hate to put it back together just to find out the tcc is bad. Tranny fluid showers are getting old. Haha
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
I don't really know, it is a 3-day weekend. How long before the new solenoid comes in. And if you really want to drive the car can install one of the solenoids and see if it works. If so, good to go. If not, it's just another pan drop once the other solenoid arrives.
If tempted to install one of them that ohms out OK, spray into the tube with some solvent to clean it first.
RemoveBeforeFlight
If tempted to install one of them that ohms out OK, spray into the tube with some solvent to clean it first.
RemoveBeforeFlight
Here's where I'm at now. I decided to install one of the tcc's that had 20 ohms. Made sure all wires were not touching and were correctly wired. I went to install the ecm I just got and then car ran like crap. Would barely idle. I have to try and get another one. I installed my old ecm and it started up and idled fine. I proceeded to take it on the highway with my powerlogger. Above 50 the tcc does lock and I can feel the rpms drop. The only thing I still have is every time I let off the throttle, I get a quick hesitation and a quick flash of the check engine light. I also get that same slight hesitation and light when I'm cruising along and touch the brake to unlock the converter. So basically I get that quick check engine light when the converter unlocks from the locked position. Not sure if that slight hesitation is just the converter unlocking. I'm not sure how smooth it's supposed to be when it unlocks but the check engine light blink is a concern for me and not sure if its still ECM related. One thing I can contribute is I now know the tcc solenoid doesn't have to click on a bench test to work. I guess I really won't know more till I get amother ECM to try.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
That isn't good on the unlock causing the hesitation and CEL flash. It may be that the flyback diode in that solenoid is open. Which would be bad for the ECM as there would be a high voltage spike being created.
RemoveBeforeFlight
RemoveBeforeFlight
*Update*
I searched for hours when I had this problem and found many threads that had similar problems/ symptoms but most of the threads just ended without telling what fixed the problem or if the problem was even fixed at all. That bugged me a lot so I wasn't going to be one of those people. Maybe this will help someone who searches and finds this thread. It ended up being the ECM I finally got a working ECM and that solved my problem. My guess is when i crosswired the TCC, I must have damaged one of the drivers in the ECM. The ECM acted normal under all conditions except when the ECM commanded lockup, that's when I would get a blip of the check engine light and a weird bucking. All of that is fixed now after the ECM swap. Now I have 2 extra TCC solenoids that I bought thinking it was them. Lol. Is there anyway I can send the ECM to someone to just fix that driver so I could have a spare ECM?
I searched for hours when I had this problem and found many threads that had similar problems/ symptoms but most of the threads just ended without telling what fixed the problem or if the problem was even fixed at all. That bugged me a lot so I wasn't going to be one of those people. Maybe this will help someone who searches and finds this thread. It ended up being the ECM I finally got a working ECM and that solved my problem. My guess is when i crosswired the TCC, I must have damaged one of the drivers in the ECM. The ECM acted normal under all conditions except when the ECM commanded lockup, that's when I would get a blip of the check engine light and a weird bucking. All of that is fixed now after the ECM swap. Now I have 2 extra TCC solenoids that I bought thinking it was them. Lol. Is there anyway I can send the ECM to someone to just fix that driver so I could have a spare ECM?
