Does anyone know what the pinouts are on the two 4T60E park/neutral - gear selector switch connectors shown in the following picture (my Chilton's wiring diagrams do not show it):

I'm having problems with my 4.9L swap - D4 (overdrive) shifts 1st, overdrive, 3rd, neutral even though D1 drives in 1st, D2 shifts 1st to 2nd, and D3 shifts 1st to 2nd to 3rd okay. I'm thinking a couple of the wires from one of the gear selector switches are backwards. I think D2 and D3 gear positions are mechanical in the transmission and actually does hydraulic shifting for a limp home mode when the ECM goes out so maybe that's why they work and D4 is still backwards in some fashion???

Here's what it needs to see during gear selection:

Hope that helps a bit. I know very little about transmissions, but had the diagram laying here. Good luck.

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Bill....I'm building my own 4.9 / 4t60E harness at the moment, and am quite interested in the answer as well.

The only wire I've been able to isolate so far from the C102 connector (the 7 prong transmission switch connector) that goes directly to the PCM is the orange wire that cooresponds to cavity A2 on the PCM 2 connector (the 24 pin connector). It attaches to the C102 connector in cavity A. The manual calls it "transmission switch input parity". I don't know if this is any help or not.

Judging from Ricr Eaters diagram, The 4 cavity C109 handles telling the PCM what gear it's in. Hopefully someone will chime in with the pinout for the C102 as well.

I was under the impression that the plug on the opposite side of the transmission was responsible for the shifting functions. Shows you how much I know.

BTW, Ricreater, thanks for the diagram.

Thanks for the diagram VA RICR-ETR!

That's just what I was looking for so I can verify my wiring back to the ECM.

Frizlefrak, here's the diagrams I have for the 3 different pinouts for the 1991 - 1993 4T60E tranmission 7-pin connectors:

1991 - 1993 "pressure switch models" shown above.

1991 - 1993 "temperature sensor models" shown above.

1991 - 1993 "no temperature sensor" models shown above.

Hope that helps you. My problem is that my swap is finished. The car starts and runs. D1 drives in 1st, D2 shifts 1st to 2nd, D3 shifts 1st, 2nd, 3rd. However, D4 shifts 1st, Overdrive, 3rd, Neutral. I'm hoping I have a wire backwards. Otherwise, I pull everything and replace the transmission. I'll ohm it out this weekend.

Thanks for your help. Plus to you.

I don't know how much of this would apply but, the cadillac mechanic who did my N* install also put a N* in a buick with a 4t60e with the N* computer contrilling the 4t60e. He found that one of the shift solenoids was backwards and used a solenoid to reverse it.

Well, I got a ScanTech hooked up to my ALDL to monitor everything while I drive my 4.9L / 4T60E in my Fiero. No codes were being thrown.

Watching the 3rd gear solenoid indicator on the ScanTech and watching the 4th gear solenoid indicator, the transmission goes free wheeling when the 4th gear solenoid reads yes on the ScanTech (when that solenoid pulls in).

Looking at the above three 7-pin connector pinout diagrams, could pin "B" be driven opposite that it should be (give dratts comment)? I don't know what the Pulse Width Modulation does, but it looks like the one diagram version at the top shows pin "B" drives a solenoid for the 4th gear clutch.

I guess I just grabbing at straws while I search for a low mileage transmission to swap in. I won't have time for a couple of months though. Would like to drive it before then. Driving the car using D1, D2, D3 manually, the car drives awesome. It hits 5k RPM in no time in each gear, then shift, and keeps pulling. Can't wait to either figure out this problem or swap the transmission.

Is it all gears 1 2 3 D N R P or P R N 1 2 3 D ? Did you turn the shift linkage around? The Fiero shifter is backwards so the arm on the trans needs to face towards the engine not away.

I was rereading this post and realized I posted nonsense previously. The mechanic I was referring to used a relay, not a solenoid to reverse the shifting solenoid. Sorry about that. Wrong information is way worse than no information.

I am doing a 4.9/4t60 swap for the old 2.8/auto in an 86 GT. Do you use the existing Fiero wiring or do you use the cadi wiring harness? I am putting the Cadi computer with the Cadi motor/trans, is it possible to just use the cadi wiring or is it impractical? The 4 & 7 pin connectors I pulled out both the male & female ends, but how do I get them to the computer in the car? There are 2 harness' going from the motor well thru the firewall, do I use wires in them or do I change them to the cadi harness'?

Ahhh grasshopper... you have an adventure awaiting...

What I did was use the Fiero harness and splice the Caddy ends on in the appropriate places. First I marked every wire from the Fiero harness with tape and marker. Then I marked every wire from the Caddy harness. Then I cut the ends off the Fiero harness and cut and soldered on the correct plug from the Caddy engine. It took literally weeks of sitting in front of the TV with manuals, soldering and cutting and marking for a couple of hours a night until it was done. I had to add several wires for the fuel injectors since the Fiero is batch fire and the Caddy is sequential. The Caddy needs 10 wires for the FI whereas the Fiero uses maybe 4 or 5. The 'connector' that goes through the firewall is not a connector but a grommet. Inside the grommet the wires are coated in epoxy. I took a dremel and carefully ground away some of the epoxy to make a channel big enough to add more wires and then I siliconed my new wires into the grommet.

Hope that helped some. Good luck with it!

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-Rick Stewart
85GT 5.0CaddyV8/Getrag 5-spd
www.V8Fiero.com