Cadillac Jim Posted September 14, 2012 Report Share Posted September 14, 2012 The process of getting OBD codes is on a Caddyinfo page linked from my signature block. Jim D's list of OBD II codes is on Caddyinfo here. My personal list, as several tab pages in an old-style (Excel 1997-2003, readable by most office software and lots of free readers) Excel file, is here and it has an OBD I section, abbreviations lists for OBD I and OBD II, severity A, B, C and D notes for OBD II codes, and other extras. I have the GM transmission overhaul manual for the model year 1997. Although I don't know my way around it like I do the FSM, I can find just about anything in there if I need to, of course. It has all the GM transmissions for the 1997 model year in there, including the 6-speed Tremec used in the CTS-V manual transmission option (it was in the 1997 Corvette). Each transmission has its own section, and I've browsed the 4T80E section a few times. Since my tranny has never given any trouble and I have it serviced by mechanics, I've never had the occasion to delve into it in detail, though. The important thing is that I have it. -- 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...
joeb Posted September 15, 2012 Author Report Share Posted September 15, 2012 the operator is manually shifting into reverse and it works. and when you shift in drive, you are in 1st gear, mechanically at least. do solenoids A and B do their dance and allow 1st gear to now work? or is car in 2nd gear? most online info says 2nd gear is the default (mechanical) gear when the electrical signals fail. i have seen some threads where the car has no reverse and no forward gears. one thread i saw said OD seemed to drop off than 3rd gear seemed to go away and finally seemed to stay in 2nd gear only as a failure mode for bad shift solenoids. that is what my car did. Link to comment Share on other sites More sharing options...
PAUL T Posted September 15, 2012 Report Share Posted September 15, 2012 I had this happen on my 94 Concours and default mode is 2nd gear. It is o.k. to drive as long as you don't rev it up too much. It is hard o gas since it is functioning at higher rpm's. The shift solenoids are not hard to change but it is messy. Just get the new solenoid kit that comes with 2 solenoids. A good tech can do it in about an hour. I think they were redesigned after 96. I remember it only cost me $75 plus transmission fluid at a mom & pop tranny shop that worked on Caddies. It was a great deal at the time. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 15, 2012 Report Share Posted September 15, 2012 I'm not aware of any transmission limp mode for the 4T80E so you may have one on me. I'll go to the FSM and see if I can find anything to help... I don't see anything on a limp mode in the FSM section 7, Transmission/Transaxle. That doesn't mean that there isn't one - in fact there almost certainly are a number of them - but the transmission modes are in the PCM software. The FSM deals with repair and is not a reference for the design details and module software; I've found things in the owner's manual that aren't in the FSM, such as guaranteed top speed (150 mph for the ETC and STS, governed to 125 mph unless the car is delivered with Z-rated tires), headlight time-out times on locking the car, etc. If you are serious about doing this as a DIY job, I think you should consider a factory shop manual (FSM). They are available new from Helm, Inc. or used at a fraction of the price on eBay. You don't need the transmission overhaul manual for repairs so don't try to find one - unless you plan to overhaul your 4T80E. Since the 4T80E is pretty much bulletproof and you can get on that it like new by doing non-tear-down repairs and maintenance from a wrecked car, I don't see a practical need for an overhaul manual for a person doing DIY on his/her own car. Nevertheless, mine isn't for sale. The transmission control schematics are on pages 7-66 and 7-77 in the 1997 FSM. The schematic shows two fuses(RLY IGN 1 10 Amp in the trunk compartment fuse block, which mainly controls the traction control input, and ECS Fuse 10 Amp, which powers the shifting and TCC relays in the engine compartment fuse/relay center - check this one!), four solenoids (one of them is the pressure control solenoid and we will ignore that one for now), two internal sensors (fluid temperature, input shaft speed), one external sensor (VSS or vehicle speed sensor, serves the same purpose as the speedometer cable in older cars by providing a signal to the PCM), and a transmission fluid pressure (TFP) manual valve that has five switches in it that together provide three signals to the PCM (Range A - Low/Reverse, .Range B - P/R/N/D4, and Range C - D4/D3). Remember, the shifter when a 4T80E transmission is used is a switch, and actual shifting is done by the PCM, so at least one solenoid is working if it shifts to reverse, neutral, and drive. A major exception is the TFP manual switch, which is operated by a shift cable running from the shifter to the transmission. There is a long list of checks and repairs for specific OBD diagnostic trouble codes (DTCs) (P0218, P0502-0503, most of those in the range P0711-0758, P1810-1814, P1860). These point to specific components or problems like individual solenoids and their circuitry. When you get the DTCs this will be a really big help. There is a repair section outside the DTC section, "No Second Gear D2, D3" on page 7-159. It's just a table of possible damaged parts that could cause the condition. The one that stands out is "1-2 shift solenoid... Stuck ON." This tells me that you will probably have DTC P0751, P0753, or both. Either will cause the MIL (multifunction lamp, or "check engine soon" light) to come on if CURRENT. Both of the write-ups on these DTCs give a casualty mode (limp mode!!!) of commanding second gear when CURRENT. If the 1-2 solenoids is stuck and the transmission can't shift to 2nd gear, this guarantees that the DTC will remain CURRENT. I also suspect a rationale that, if the transmission ever does manage a shift to 2nd gear, the car can be driven almost normally until you can get it home or to a garage. -- 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...
joeb Posted September 15, 2012 Author Report Share Posted September 15, 2012 i am going down to folks on tuesday. i had no codes before and dont expect any on tuesday. ECS fuse underhood? now that would be a bummer to yank trans and find fuse is blown after its back in. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 15, 2012 Report Share Posted September 15, 2012 The fuse is a long shot but it should be checked first. If you mean that "it didn't have any codes before" meaning after the tranny stuck in low or second gear, that looks like a stuck solenoid. Even a stuck solenoid should throw a code, though. -- 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...
Texas Jim Posted September 15, 2012 Report Share Posted September 15, 2012 i am going down to folks on tuesday. i had no codes before and dont expect any on tuesday. ECS fuse underhood? now that would be a bummer to yank trans and find fuse is blown after its back in. That pic looks liek an old Willis... Link to comment Share on other sites More sharing options...
joeb Posted September 19, 2012 Author Report Share Posted September 19, 2012 dropped pan. fluid is frothy light red. like a cherry smoothy. smells fine. no debris in pan. both solenoids are old style. no retainer clip on small screen. both solenoids are clocked the same direction. both measure 2.3 ohms? the other valve bodies i took apart had 1 of the solenoids turned 90 degrees. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 19, 2012 Report Share Posted September 19, 2012 As for the solenoids, if I was looking at them, I would replace them. Solenoids that are OK electrically may still stick or even be broken in ways that are not obvious. New ones should be the later revision and last the life of the car, and this will help prevent going back into the transmission. You might think about the usual transmission servicing stuff like filter and gaskets, of course. I haven't done this job myself; wait for BodybyFisher, Ranger, or others that have done transmission work on the 4T80E to chime in. -- 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...
joeb Posted September 19, 2012 Author Report Share Posted September 19, 2012 The large metal, clad separator plate of course shredded when i took valve body apart. $50 dealer cost. The junkyard valve bodies had perfect plates when I took them apart. But yard will only sell trans. Not parts. And trans are as-is. No work, get another. And u pull. So, it's reseal. Hope it works. Or find another trans. Or rebuild? Local guy will rebuild and replace all broken parts for 650. Carry out. Link to comment Share on other sites More sharing options...
BodybyFisher Posted September 19, 2012 Report Share Posted September 19, 2012 This thread kind of delved right into the shift solenoids as the cause, I think. Do you have any codes indicating a shift solenoid problem? If you are talking about the rubberized spacer plate, I replaced mine also Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
joeb Posted September 19, 2012 Author Report Share Posted September 19, 2012 No codes. Trans will not shift. So I assumed it may be solenoids. I see so many threads discussing solenoids I figured it was good guess. Car is at dads. 100 miles away. He has many tools. Nice shop. Wish I would of done my heads there 5 yrs ago. He ordered plate and it will be in tomorrow. Guess this is my "tranny blog"? Just luck I was home when trans acted up. Maybe change thread to say "trans?". Link to comment Share on other sites More sharing options...
BodybyFisher Posted September 19, 2012 Report Share Posted September 19, 2012 Hmm, from 96 on, a bad shift solenoid sets a code, someone confirm this for me. Also confirm, can a shift solenoid be bad WITHOUT setting a code? I am kind of surprised that this tranny won't shift without setting a code Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted September 20, 2012 Report Share Posted September 20, 2012 It's possible that the solenoid could be cracked which could jam the solenoid plunger. I don't know if it would set a code or not. Throwing a set of solenoids at it may fix the problem if you were lucky but it seems my luck never is that good... Reading this thread, it sounds like joeb's valve body is out of the trans. If it were my car, before I threw new solenoids at it, I'd remove the solenoids and inspect them for cracks in the housings. If the solenoid plunger can't be moved under finger pressure, battery voltage could be applied to the solenoid plug (with it disconnected from the trans. harness) and see if the plunger moves, If it doesn't, I'd say the solenoid was bad. If both solenoids pass those crude tests, I'd re-install them and button the trans. up and have a dealer run the garage shift test with the Tech-2 hooked up. That should narrow the source of the problem. The 4T-80E transaxle is a very durable unit. The trans. shop near me says the only things they need to do to them is an ocassional torque converter clutch solenoid, shift solenoids, and an ocassional torque converter. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
joeb Posted September 20, 2012 Author Report Share Posted September 20, 2012 yes. VB is out. i have a 12v power supply and can test solenoids to see what they do. i see how the plastic nipple on end pushes against VB spool valve. i thought perhaps solenoid allowed fluid pressure to pass thru but it is mechanical in that a plunger extends and pushes spool valve? with solenoid in hand, you cannot see the plunger. or rather, it is not extended. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 20, 2012 Report Share Posted September 20, 2012 Try the solenoid at 5 Volts before you try it at 12 Volts. The PCM operates the solenoids with a PWM (pulse-width modulation) signal and sometimes these are at lower voltage. -- 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...
Cadillac Jim Posted September 20, 2012 Report Share Posted September 20, 2012 P0750 Shift Solenoid A Malfunction P0751 1-2 Shift Solenoid Valve Performance - No First or Fourth Gear P0752 1-2 Shift Solenoid Valve Performance - No Second or Third Gear P0753 1-2 Shift Solenoid Circuit Electrical P0754 Shift Solenoid A Intermittent P0755 Shift Solenoid B Malfunction P0756 2-3 Shift Solenoid Valve Performance - No First or Second Gear P0757 2-3 Shift Solenoid Valve Performance - No Third or Fourth Gear P0758 2-3 Shift Solenoid Circuit Electrical P0759 Shift Solenoid B Intermittent P0760 Shift Solenoid C Malfunction P0761 Shift Solenoid C Performance or Stuck Off P0762 Shift Solenoid C Stuck On P0763 Shift Solenoid C Electrical P0764 Shift Solenoid C Intermittent P0765 Shift Solenoid D Malfunction P0766 Shift Solenoid D Performance or Stuck Off P0767 Shift Solenoid D Stuck On P0768 Shift Solenoid D Electrical P0769 Shift Solenoid D Intermittent P0770 Shift Solenoid E Malfunction P0771 Shift Solenoid E Performance or Stuck Off P0772 Shift Solenoid E Stuck On P0773 Shift Solenoid E Electrical P0774 Shift Solenoid E Intermittent P0780 Shift Malfunction P0781 1-2 Shift Malfunction P0782 2-3 Shift Malfunction P0783 3-4 Shift Malfunction P0784 4-5 Shift Malfunction P0785 3-2 Shift Solenoid Circuit Electrical P0786 Shift/Timing Solenoid Range/Performance P0787 Shift/Timing Solenoid Low P0788 Shift/Timing Solenoid High P0789 Shift/Timing Solenoid Intermittent P0790 Normal/Performance Switch Circuit Malfunction P0801 Reverse Inhibit Control Circuit Malfunction P0803 1-4 Upshift (Skip Shift) Solenoid Control Circuit Malfunction P0804 1-4 Upshift (Skip Shift) Lamp Control Circuit Malfunction -- 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...
KHE Posted September 20, 2012 Report Share Posted September 20, 2012 Good point Jim. I did not know that was a PWM signal. I thought the solenoid was either ON or OFF to provide 4 combinations for the four gears. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
joeb Posted September 21, 2012 Author Report Share Posted September 21, 2012 got plate. have not had chance to work on trans yet. i talked to trans shop. they said the color of fluid sounds like water contamination. i did change radiator 4 yrs ago with cheap aftermarket version. i checked coolant level last week and its right at normal mark. i have not added any in 4 yrs since i did heads. shop just said weird fluid color is probably clutch material flaking off due to water contamination. Link to comment Share on other sites More sharing options...
KHE Posted September 21, 2012 Report Share Posted September 21, 2012 Transmission fluid will lose it's bright red color over time since the red is a dye that is added so the assembly plants do not confuse it with motor oil. If it were me, I'd get a second opinion on the diagnosis. The local transmission shop by me who has a stellar reputation told me they rarely if ever need to do a total rebuild. Just an ocassional torque converter clutch seal, solenoid, etc. The shop manual has a specific test called the garage test where the car is supported on a hoist and run with a Tech-2 hooked up. From there, a complete set of diagnostic charts follow. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
joeb Posted September 21, 2012 Author Report Share Posted September 21, 2012 You would scratch your head if u saw this fluid. It looks like baileys Irish cream. I Changd the condenser in June and took out the radiator. I collected the coolant of course but really only dripped a couple of tbs of trans fluid. I am not sure if I even topped off the trans fluid. It was a nice reddish color. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 21, 2012 Report Share Posted September 21, 2012 It does sound like there is coolant in the fluid. It is probably worthwhile to button it up and flush the fluid before you go for the clutches, which probably means a full overhaul. In the meantime, you might try a pressure test of the cooling system, and watch for coolant dripping out of the disconnected transmission cooler connections. -- 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...
KHE Posted September 22, 2012 Report Share Posted September 22, 2012 Baileys.....Yummmm.... Maybe the trans. shop is right after all. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
joeb Posted September 22, 2012 Author Report Share Posted September 22, 2012 i cut open a solenoid. the small pin on right is fully extended. it pushes against steel ball and into plastic bore to the left and controls fluid flow. i suppose if solenoid clicks that means plunger is moving. hard to tell unless you cut solenoid apart Link to comment Share on other sites More sharing options...
Cadillac Jim Posted September 22, 2012 Report Share Posted September 22, 2012 Does the plunger move when it clicks? -- 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...
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