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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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Discussion Starter #1
96 Deville, throwing the following codes

TC 0025
TC 0035
TC 0037

I'm assuming these are all wheel speed sensors, does this mean that I have to change three wheel bearing hub assembies, or could it be the traction control system?

Also, I only have 2nd gear, no other gear at all. Could this be tied in with it, or would this be the shift solenoids? Do shift solenoids throw codes if they fail?
 

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White Diamond '03 DHS (with DTS floor shift)
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'96 should be OBDII but those are OBDI codes.
T025 ................................................... LF Wheel Speed Sensor Fault
T035 ................................................... LR Wheel Speed Sensor Fault
T037 ........................................ LR Wheel Speed Sensor Continuity Fault

Odd to have both left side sensors fail at the same time. I'd look for some common wire or connection.
 

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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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Discussion Starter #3
So would this have something to do with the tranny staying in 2nd- taking off in 2nd and NOT shifting into 3rd or 4th?
 

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White Diamond '03 DHS (with DTS floor shift)
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Absolutely. Inop ABS disables T/C which in turn disables 1st gear.
 

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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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Discussion Starter #5
OK this is going to sound weird- but in testing the transmission (since my dad doesn't currently have valid license plates on the deville) I think I may have set those codes off myself- I had both front wheels jacked up off the ground to test gears in the back yard, of course the back wheels don't turn then, so what does the PCM do? It will obviously sense wheel speed at the front, but not at the back- will it think that the rear speed sensors are defective? What happens when a car like this is run on a dyno- say for Ontario emissions tests? Two wheels running and two standing still?

Anyway, we took the car off the road when we found out the tranny wasn't shifting into 3rd or 4th, so this is my only method for testing right now. Don't want to license the car until I know the transmission is working. My next step is to change the shift solenoids, I've got a spare transmission from a 1997 Aurora (4T80-E) so I've got the parts.

After I thought about what I was doing, I let the car down, cleared all the codes and drove it around the yard a bit. It hasn't thrown a TCS code since...

Stuck in second- no first, third, or fourth gears- checked the trans filters and they were clean- oil was clean too. I don't think anything is worn out, it has just over 100,000 miles (171,000 kms).

Anyone who wants to throw their two cents worth in, is very welcome to do so. And thanks Ranger for the responses.
 

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White Diamond '03 DHS (with DTS floor shift)
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I had both front wheels jacked up off the ground to test gears in the back yard, of course the back wheels don't turn then, so what does the PCM do? It will obviously sense wheel speed at the front, but not at the back- will it think that the rear speed sensors are defective? What happens when a car like this is run on a dyno- say for Ontario emissions tests? Two wheels running and two standing still?
That is why they no longer do emissions testing that way.

Stuck in second- no first, third, or fourth gears
Sounds like shift solenoids.
 

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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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Discussion Starter #7
I've downloaded a manual on 4T80-E transmissions.

OK I've manually energized the shift solenoids with 12 volts by disconnecting the trans harness connector and, using a part of an old wiring harness, put direct power to the solenoids. I heard each of them click inside the transmission. Also, in diagnostic mode, the "ECON" and "DEFOG" indicator lights do not light up, while I've got the car jacked up and in gear, even up to 50 MPH- it stays in second. And the "E" symbol is not lighting up, so "trans shift adapts are enabled".

So I'm a little lost right now, it's almost as if the PCM is not doing it's job energizing the shift solenoids. Just checking the codes again, it's throwing a P0018- coolant circuit high. Could this have something to do with shifting?
 

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Discussion Starter #9
Turns out in the engine swap I forgot to connect the coolant temp sensor- but that has nothing to do with the trans, it's still not shifting. Might have weak solenoids- or low line pressure- this is getting frustrating. If I had a spare transmission with the correct final drive ratio I'd just swap that in, but the only other 4T80-E's that I have are 3.71:1 and 3.48:1. (Mine is 3.11:1)

If I can't get this going soon I think it's time to visit a Cadillac Dealership for some diagnostic work.
 

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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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Discussion Starter #10
PROBLEM SOLVED!!!!!!!!!!!!!!!!!!!!!!!!! All gears working & shifting perfect.

I dropped the pan and noticed one shift solenoid was not parallel to the other- one was cracked on one side and bent at an angle, and also there's a plastic plug between the two solenoids that is supposed to be held in with a metal bracket with a bolt from the top- (it helps to be able to take another transmission apart and look at it) and that metal bracket was NOT there. I just put the valve body assembly in from the other 4T80 I have and I've got all forward gears now.

My dad bought the car a few months ago for $725 from a real estate rep in Mississauga, Ontario- knowing it had a blown engine. Changed the engine and found out only 2nd gear was working. I'm not surprised the engine was blown, the real estate rep said that he just passed a car on the freeway and got back in the slow lane and it just gave out a "bang". I'm surprised he didn't realize he was driving around in 2nd. The RPMs must have been sky high.

He told me he always had it serviced at the Caddy dealership where he bought it- who ever worked on that transmission really messed up- forgetting to reinstall that metal bracket, and possibly damaging the shift solenoid (I'm pretty sure it didn't snap on it's own). Makes you wonder which shop/mechanic you can really trust.

Thanks for all the help and responses.
 

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White Diamond '03 DHS (with DTS floor shift)
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The metal bracket is a part of and updated kit to prevent the cracked solenoid. The one with the bracket has had the problem before and was repaired. The one without it is original and just failed. If you ordered new solenoids, they would come with the bracket. I think newer one probably do have it installed at the factory, but I am not sure when that happened.
 

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Discussion Starter #12
My mistake, I figured it would have been a mechanic's poor repair job. Well it's good to know- because I've now got plans to haul my 97 Eldorado into the garage and pull the pan off- if it doesn't have that metal bracket I'm going to install one to be on the safe side- I wouldn't want to be on a long trip somewhere and wind up all of a sudden only having 2nd gear...

Thanks a bunch Ranger- I hope this helps others too if they ever run across this...

That 96 Deville is scheduled for a trip this week to West Texas- see how it goes. The only other thing I'd worry about taking a Caddy on a long trip is the notorious HG problem- what if that happened in the middle of a 1600 mile trip? $$$$$$$$............ Hopefully that never happens to ANYONE. Luckily when my Eldo's gaskets (or rather head bolts) gave up it was only an hour away from home. After that I could only travel at reduced speeds before the engine would heat up.

And for anyone who wants it, I found a 113 page manual on the internet about the 4T80 transmission, it's in PDF format- just send me an email- jakemwiebe[AT]hotmail.com and I'll forward it to you- it was a big help to me.
 
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