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Jerry Newton
Jerry Newton, Cadillac Technician
Category: Cadillac
Satisfied Customers: 4508
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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Cadillac Eldorado ETC: I have a 1996 Cadillac Eldorado Touring

Customer Question

I have a 1996 Cadillac Eldorado Touring Coupe. The transmission works just fine until exactly 35 miles per hour, then it goes haywire. Back below 35 and it works fine again. Transmission Speed Sensor?
Submitted: 1 year ago.
Category: Cadillac
Expert:  Jerry Newton replied 1 year ago.
Any check engine lights or anything like that? What does it do at 35 mph exactly? Does the speedo jump around at all when this occurs?
Customer: replied 1 year ago.
The speedometer does kind of go funky at 35 mph. The tach goes nuts, also. It shifts out of gear and the engine revs. Back at 35, it calms back down. Do have a check engine light, and a "Service Transmission" message on the dash.
Customer: replied 1 year ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Jerry Newton replied 1 year ago.
Let's start with trouble codes, are you familiar with retrieving trouble codes on this car? No tools necessary, I can walk you through the procedure if you like.
Customer: replied 1 year ago.
TC0037 TC0027 are the codes I get. I replaced the speed sensor and it still does it. The Speedometer does not act up, but when it gets to 35mph, or about 3100 RMP, it shifts itself into neutral. If you get off, it goes back into gear.
Customer: replied 1 year ago.
I know it has a bad wheel bearing, and I have ordered two new wheel hub assemblies for the front. I will install them next week.
Expert:  Jerry Newton replied 1 year ago.
Those TC codes are relative to traction control/ABS, and don't affect speedometer or transmission function. Let's gloss over those for the time being. No PCM codes?
Customer: replied 1 year ago.
Here's what else I discovered. It runs fine up to 50mph (that's as far as I took it) in third gear. It does not cut out, whatsoever. But in regular "drive," it shifts to neutral at 35mph (about 3100 rpm).
Expert:  Jerry Newton replied 1 year ago.
These transmissions, back in the early days (93-97) had problems with shift solenoids breaking or cracking. You can pull the pan, and just push against the solenoids and see if one is cracked or broken. It's due to a design flaw, where there is a screen that pushes against the solenoid with enough force to break it. You install revised parts that correct this issue, parts available from GM for $70 or so. I think this is where you're at, frankly. I'd be taking the pan off and having a look at those solenoids.
Customer: replied 1 year ago.
Thanks. That was going to be my next move - if I can find anyone locally who has the solenoids. Local parts stores tell me it will be a week. I can go on the internet and get them quicker than that. Thanks again.
Expert:  Jerry Newton replied 1 year ago.
Sure, good luck with it. If you need any help with this, let me know. FYI: the valve body has to be removed from the car to service these solenoids, you can't replace them with the transmission assembled.