The Mad Scientist Posted December 12, 2014 Report Share Posted December 12, 2014 Afternoon guys. First off im new to the forums and want to say hello. Second this is my issue. ive got a 80k miles Cadiliac Eldorado 95 model and she is throwing a P056 Transmission speed input sensor code... Now im not sure if this is a common problem with these transmissions but it is the 4T80E trans front wheel drive model. I love this car and right now its the only thing i have. it was bought for me by my Father for $900 and im just wanting to get the car back to as close as new as i can for school. the only code it is throwing is that same P056 error but i have lost Overdrive now but the trans is still very strong and i have put my foot in it to make sure its not soft. This Cadiliac is my first one i have ever owned or driven so any help is appreciated. Link to comment Share on other sites More sharing options...
barczy01 Posted December 13, 2014 Report Share Posted December 13, 2014 It twas a common problem in 1994,95 cadillac's for the P056. It's a sensor deep inside the side cover of the transmission. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted December 15, 2014 Report Share Posted December 15, 2014 You might try servicing the transmission to see if that will help but it probably won't change anything. Avoid driving at highways speeds up mountain grades and don't tow with the car, but it should be find around town indefinitely. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
The Mad Scientist Posted December 15, 2014 Author Report Share Posted December 15, 2014 will the sensor cause any internal damage to the transmission driving it on the interstate? because this is my car to get back and fourth from my hotel to school for a year and i have to go interstate for it. Also my familiy lives 5 hours from me and i will be going to see them shortly. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted December 16, 2014 Report Share Posted December 16, 2014 If this code means that the TCC doesn't engage, then it shouldn't harm the car to drive it. Interstate is fine, just not across the Rockies or Appalachians, or in and out of Jackson, WY. But there are exceptions. A Caddyinfo member drove his with the TCC stuck off for a long time and it turned out that the TCC slippage generated debris which eventually ruined his transmission. But that's rare. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
The Mad Scientist Posted December 16, 2014 Author Report Share Posted December 16, 2014 ok so if the system just recently lost overdrive from this error code i should be able to replace the sensor without much damage right? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted December 17, 2014 Report Share Posted December 17, 2014 The P056 is a sensor code, not a TCC code: " Transmission Input Speed Sensor" It depends on what you mean by "lost overdrive." In the 4T80E, the 4th gear is an overdrive gear; if you lost 4th gear, you need to get the transmission fixed ASAP, or get a used one from a recycling yard. If you have four gears but the TCC doesn't engage, there are several reasons for that, none of them the sensor. I don't know that much about TCC failures and OBD 5 codes, but this looks more like an electrical problem or sensor failure. Electrical problems are a lot more common than sensor problems. I would start by checking out the wiring harness and connectors to the transmission, especially the big connector near the transmission. Make sure that none of the terminals are pushed back into the connector and that they are all clean and tight. Anyone here familiar with changing the input speed sensor on a 4T80E? -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
The Mad Scientist Posted December 30, 2014 Author Report Share Posted December 30, 2014 Ok so an update on the issue. I replaced the Transmission input speed sensor and it cleared the P056 error code. But now i have a new error that seemed to come on after the sensor was replaced. its throwing a P029 error code. from what i have seen on the inside of the Trans it is still clean. i mean hell the filters were not even clogged up. both trans pans were clean and free of debris. from what i have read and what the error code is saying its saying that the shift solenoids for overdrive are gone..... any suggestions? Link to comment Share on other sites More sharing options...
winterset Posted December 30, 2014 Report Share Posted December 30, 2014 Were any connectors unplugged, and maybe a pin is loose or bent? Other than that i believe the shift solenoids in the '95 model year were without a support bracket on the shift solenoids that caused solenoid failure. The new solenoids come with the bracket. This job can be done by dropping the transmission pan. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted December 30, 2014 Report Share Posted December 30, 2014 P029 (E029) Transaxle Shift 'B' solenoid problem (1st, 3rd, 4th gear) -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
The Mad Scientist Posted January 2, 2015 Author Report Share Posted January 2, 2015 Last Update. Problem is solved. replaced the two shift solenoids with new parts and the transmission is now working back as it used to when i first got the car a little over 8k miles ago. i think the P056 error code was masking the more severe problem of the P029 error code that did not set untill after the TSS was replaced. From what i seen no connectors were damaged, loose, or undone inside the trans but when i was looking at the old solenoids they felt loose in thier housing bores. the new solenoids felt tighter in the bores and the transmission actually shifts smoother than when it was when i first got the car. on a side note these 4T80E transmissions for these 4.6L Northstar FWD cars are Thirsty buggers...... 3 gallons of trans fluid?? YEESH! But hey im not complaining im just glad to have my Cadillac back. Thanks for the input guys. Link to comment Share on other sites More sharing options...
winterset Posted January 2, 2015 Report Share Posted January 2, 2015 Congrats. I am impressed how quick you work. Did these new solenoids have the reinforcement bracket? Also, now that your transmission is fixed, and fluid changed, have you considered draining and refilling your antifreeze? Its recommended to do this every 2 years for the green, and every 4 years for the orange. Changing brake fluid, and power steering fluid every so often is good too. Power steering can be done with a turkey baster, and brakes can be bleed at each caliper. There might be a thread on this forum on recommended maintenance on the older N*'s Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 3, 2015 Report Share Posted January 3, 2015 Congratulations on your success! Most automatic transmissions will take over twice what is needed to top off after a transmission service because of the capacity of the torque converter. If you used Dexron VI to refill after your work, you will have perfect shifting even that first shift on a cold morning, due to the better control of cold viscosity of Dexron VI. Also, Dexron VI provides 230% of the clutch wear of Dexron III, so your transmission may have more clutch life in it now than it did when it was new. There is a third transmission solenoid, for the TCC solenoid. You don't need it unless you have P039 and other TCC-related electrical codes. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
SevilleDorado Posted January 22, 2015 Report Share Posted January 22, 2015 Sounds like you did a great job, and glad it worked out for you so well. My question is - did the new selenoids come with the above bracket someone mentioned ? I just bought an ACDelco selenoid for my 95 Seville and it had no bracket........I also got the pan gasket scavenger screen kit too. So you were able to change out the selenoids with only dropping the pan ? Thanks - Link to comment Share on other sites More sharing options...
winterset Posted January 22, 2015 Report Share Posted January 22, 2015 http://www.ebay.com/itm/4T80E-Transmission-Shift-Solenoid-Update-Package-Set-Kit-Pair-A-B-Cadillac-4T80-/230501388343 Here is an acdelco shift solenoid pair and upgrade bracket kit for $38 with free shipping. Each solenoid is different with a different part number and are not interchangeable (per GM procedures) I'm not sure what model or year needed the upgraded bracket. Some cars may have it already. Also mark the torque sequence with black marker on the pan with a new gasket so you can put it back on correctly and a little easier. And consider draining the side plug and filling with Dexron vi Link to comment Share on other sites More sharing options...
SevilleDorado Posted January 23, 2015 Report Share Posted January 23, 2015 Thanks , ordered that set up for my ElDorado last night - it's a 95. Running a repair on the Seville right now it is also a 95 . That selenoid is the one that came without a bracket . I also found a 1/8" stell ball in the pan when I took it off - ........... Link to comment Share on other sites More sharing options...
The Mad Scientist Posted March 3, 2015 Author Report Share Posted March 3, 2015 and im sorry for the slow reply but yes the new solenoid kit came with a bracket in the kit. i think it took me about 2 hours to change the solenoids and re install the lower valve body on the bottom of the trans Link to comment Share on other sites More sharing options...
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