Contour Enthusiasts Group Archives Forums General Troubleshooting Yeah, but where's the ground?

So here is my problem...

When my tranny shifts from 3rd to 4th there is some noticable "chugging" going on just before the shift. Also, during very lite throttle application while in 4th.

Here is what I have been able to find out so far...

Ok! So I have been carrying with me a P0743 code for quite some time (ever since the car was in the shop the last time because of a botched tranny job!!). I know that code means that there is an electrical circuit problem with the torque converter clutch solenoid. I also know that the solenoid is engaged by the PCM grounding the solenoid.

I have an article that outlines the pins of the torque converter solenoid. The entire article can be read here, with information being on pages 3,4&5. I will list the pin names here though...

Pin 1 = TFT Signal
Pin 2 = Signal Return
Pin 3 = TCC Power In
Pin 4 = TCC Signal From PCM
Pin 5 = SS2 Signal From PCM
Pin 6 = Shift Solenoid Power In
Pin 7 = SS1 Signal From PCM
Pin 8 = 3-2T/CCS Signal From PCM
Pin 9 = EPC Power In
Pin 10 = EPC Signal From PCM

Which leads me to what I don't know...

Ok! So which one of these is the ground? I am guessing that it would be Pin 2, but I am just not sure. I know to check the obvious things such as the Power In and what not, but if someone could give me some insight what the others are, such as Pin 5, 7, 8, 9, & 10 it would help me out a great deal.

Since I don't have a scanner that I can use to moniter all this at the sametime, I will use my Fluke DVOM and check to see if voltages are switching while driving one by one. Any additional input here would help out a lot too.

Thanks for anything at all. Hell even a smile or two would help me at least feel a little better.

I can recite the internal schematic info from Ford wiring diag for you below which may assist.

First, pin info I have is mirror image to article, i.e., pins 2 & 9 match all others are flipped. Pin 1 should have Gn/W wire and pin 10 Bk/O.

There is no ground connection in the sense of -12 volt chassis ground. All ground connections are provided via PCM. Three +12 (hot in run) connections for solenoids are provided; TCC, EPC and S1/S2/TCCoast. Each solenoid has a separate connection to PCM. TFT is variable resistor and has its own pair of terminals. Total 3+5+2=10 pins.

Thanks horseydug, that helps out alot. First I have to check if all parts are getting proper voltage then see if they are switching at the right times. Your info will help me shed some light on this situation. Thanks alot!!

Hey BK! Those smiles work too man. Thanks!

Here is the information that I was able to gather in a few short runs... Don't worry, I have all the necessary extenstions needed to safely do this while driving.

On Pin 4, TCC signal from PCM, this is what I got.
Gears 1-2 = 85-90 mV
Gears 2-3 = 85-90 mV
Gear 3-4 = 300 mV

At the shift point for 4th, the meter would peak out and then settle, after the shift, to a little above the 300mv range. When slowing to a stop, with brake applied, the voltage would drop back to 85-90mV range once the RPMs reached 1250. If you coasted to a stop, voltage would not drop until you applied the brakes. When this voltage drop occurs, you do feel what feels like a down shift. Presumably, this is the torque converter unlocking. (?)

On Pin 6, Shift Solenoid Power In,

Gears 1-2 = 175mV
Gears 2-3 = 175mV
Gear 3-4 = 14V

While in Park at idle, 175mV - 180mV.
When car is put into drive and you begin moving, voltage drops slightly to 150mV range. Ok! But here is the thing that I noticed during this test. After reaching 4th gear and the voltage reached 14V, soon after, the meter would peak out, the chugging would happen, the tranny would seemingly downshift, RPMs would raise about 250 RPMs and then the voltage would settle back to 175mV. It seems like I am loosing the signal from the PCM at this point.

I am wondering if my Turbine Speed Sensor could have something to do with this. I pulled the connecter on it last weekend and found all sorts of sand and grit in there. Not just around the inside of the connecter, but also in the ports for the connecters. I cleaned it out the best I could. I of course reset the computer.

Any thoughts on what I have gathered so far. Are there some other things that I might could check using the above method?

Thanks

Can you confirm the wire colors I mentioned since I'm unable to make sense of your voltage readings.
If you are measuring power in to solenoid then battery voltage should be measured at all times. If measuring out from solenoid to PCM then you should measure bat volts when PCM is not providing ground path (assuming zero PCM leakage) and the voltage drop across PCM when it is conducting to ground.

Well I just went outside and checked the wire colors, they do not match. That is not the only thing, but I will get to that in a moment.

These colors are from the wiring harness.

Pin 1 = Blk/Red
Pin 2 = Grn/Red
Pin 3 = Blk/Brn
Pin 4 = Blk/Grn
Pin 5 = Grn/Org
Pin 6 = Blk/Wht
Pin 7 = Grn/Yel
Pin 8 = Grn/Wht
Pin 9 = Red
Pin10 = Wht/Red


The way I checked the voltages was by grounding one of the probes to the negitive battery terminal plate and inserting the other into the backside of the plug (PCM side) of the TCC Solenoid on top of the tranny.

I was questioning the voltages myself, since I was never recording 12V at anytime. With engine running, I was only able to measure 6V from Pin 4. After I put the tranny in gear and start rolling, everything went to mV. Although you see that it is switching, but why in mV's? I made several runs for each of the measurements that I took above to verify everything, so I am wondering if my Fluke is fluking out on me.

As for the other thing that I mentioned above... It states in the article that there are two different solenoid assemblies. One with a black connector is a low impedance assembly (1.0-2.0 ohms) and the other is a high impedance (12.5-19.0 ohms) with a beige connector. The resistance can be checked across pins 3 and 4 to check this. Well I have a black connector(on the solenoid assembly) and I check the resistance across pins 3 and 4 and got 20 ohms? It also states in the article that the low impedance assembly should not be used in any CD4E beyond the 95 model year. So now This really confuses the hell out of me because I have a black solenoid body and the resistance measures 1 ohm over what the high impedance should. I should have the high impedance assembly in mine since I have a 98.

I've added manual info alongside your observations:

Pin 1 = Blk/Red .. Gn/W +12 to TCC
Pin 2 = Grn/Red .. Br/R TFT
Pin 3 = Blk/Brn ... W/R TFT
Pin 4 = Blk/Grn ... Bk/Y SS1 to PCM
Pin 5 = Grn/Org .. Gn/Y +12 for SS1, SS2 & timing/coast
Pin 6 = Blk/Wht .. Bk/Bl SS2 to PCM
Pin 7 = Grn/Yel ... Bk/W TCC to PCM
Pin 8 = Grn/Wht .. Bk/R EPC to PCM
Pin 9 = Red ........ Gn/O +12 to EPC
Pin10 = Wht/Red .. Bk/O timing/coast to PCM

Connector shows as round with a flat side up. Pins numbered:
1 2 3
4 5 6 7
8 9 10

I think I'd start by trying to get a +12 volt reading, try with key on, but engine off. Don't think one ohm a big diff.

Ok thanks. There has to be a something that I am missing here then. I will print out the thread, look everything over and go back to the car when I have more time. The information that you have provided has helped a lot.

I am sending off for that Ford Service CD Monday!!! I hope that it can help me understand why our wiring information is different, because the plug description that you give is correct. Or maybe at least prove that I am color blind when working on cars, . Either way... Thanks again for all your help.

My colors match between '97 Ford wiring manual and '98 CD.
I'm color blind (red/green) and 10% of males are: I was wondering about you.