Malfunction Indicator Light with P0741 and P1860
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  1. #1
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Malfunction Indicator Light with P0741 and P1860

    I was able to fix this problem last spring, and another forum user just asked about it, so I am posting the problem and a solution in case someone else can take advantage of the alternate fix that avoids removing the transaxle. The problem was on a 2001 Seville SLS with a 4T80-E automatic transaxle. The malfunction indicator light was on and P0741 and P1860 codes were indicated on the drivers’ information screen in the dashboard. (Press and hold two of the driver info buttons at the same time to view the codes on the Seville.)

    The trouble codes were:
    P0741 indicating a problem with the torque converter clutch solenoid valve.
    P1860 indicating a problem with the TCC circuit.

    Last summer the Cadillac dealer proposed a new transmission so I took it to a trusted transmission shop instead. The transmission shop verified the transmission was operating properly and suggested the problem was electrical. They said to ignore the light and keep driving. The decision tree in the factory service manual lead to the PCM, so in another attempt to fix the pesky light I had a Tech II repair shop replace and program a new PCM which did not fix the problem. They insisted that the problem was with the mechanical components of the transmission. Considering the difference in opinion by the repair shops and after spending the money on a replacement PCM, I got used to the light ... until the car failed emissions due to the P0741 code.

    I thought about the benefit of having the MIL light available when I really need it so I decided to look into diagnosing the problem myself. After a thorough reading of the service manual and testing the wiring for shorts or opens, I checked the resistance across the terminals of the torque converter clutch pulse width modulated (TCC PWM) solenoid valve. There should be 10-15 ohms, but was no resistance which indicates a bad solenoid valve. (If the decision tree in the service manual told us to check this, it would have saved the cost of a PCM.) The quote from the transmission shop for replacing the valve came in around $1500 because they said the transmission had to come out to replace it. The transmission shop suggested obtaining a repair waiver because the cost of repair outweighed the cost of obtaining a waiver and the problem does not harm the transmission. The service manual confirmed that the transmission should be removed to replace the valve. The Tech II repair shop disagreed with the bad solenoid diagnosis and proposed that they run a diagnostic check on their computer. I didn't bother because I already knew what the problem was.

    Inspired by someone who said the transaxle can be removed without taking out the motor, needing the MIL light fixed, and considering the savings in gas mileage that I would get when the TCC PWM did its thing, I decided to replace the valve myself. But I decided first to try to replace the solenoid without removing the transaxle and it worked. So when someone else has this problem here is the procedure. I hope someone is able to make use of it.

    PROBLEM:

    MIL light on with both codes P0741 and P1860.

    TROUBLESHOOT:

    Step One: Road test the TCC PMW solenoid valve operation: Operate the car in drive (D) at a constant speed of 50 mph. Leaving your foot on the gas, observe the tach while tapping the brake lightly with your other foot. The tach should go up briefly and then down. The rise is is a result of the TCC disengagment which allows transmission slip. The drop is because your car slowed down when you taped the brakes. You can also see the tach drop when the TCC engages after the test.

    Step Two: Test the TCC PWM solenoid valve on the transmission side of the AT inline 20-way connector with an ohmmeter. There should be 10-15 ohm of resistance. The two terminals are U and T, which are the two pins to the right on the upper row when viewing the connector with the alignment tab to the right. If there is zero or infinite ohms resistance the solenoid is most likely bad. The wiring between the connector and the solenoid could also be shorted or open. (In my case there was zero ohms.)

    Step Three: If the solenoid and wiring on the transmission side are good, look at the wiring on the engine side of the connector. When viewing the connector with the alignment tab to the left the connectors are the two left holes on the upper row. There should be no voltage with the ignition off and voltage with the ignition on and the car not running. Disconnect the C2 connector at the PCM and check for shorts from the upper left or T terminal and other wires or to ground to verify the wiring is OK.

    Step Four: If the wiring and solenoid are good, then look into the PCM.

    FIX:

    To replace the TCC PWM solenoid with the transmission in the car. Verify that there is enough room to get your fingers between the transaxle side cover and the car body, because after moving the side cover, you will need to get at least one finger in there to press in the hairpin.

    Remove the parts required to get at the side cover and everything between the side cover and car body. You will need good access to the upper rear corner of the side cover. Remove the upper engine mount in the left front wheel well. The lower bracket can stay in place if the frame studs are removed from inside the engine compartment. Loosen the side cover and catch just over a quart of transmission oil that comes out. Move the side cover open as far as possible. It cannot be removed. The TCC PWM solenoid is located at the upper rear corner and is attached with a hairpin that is just behind it. You should be able to feel the end of the hairpin with one finger. It will move up and down easily. You can see the end of the hairpin with the aid of a mirror on a stick.

    Pull out the hairpin with a pick or bent needle nose plier. If you use a pick it will fall to the bottom of the side cover where you must retrieve it. Inspect the solenoid. Mine had a hairline crack in the solenoid plastic because it was old and brittle. It was probably due to expansion and contraction due to heat. I verified the operation of the TCC clutch with a drive test so the turbine shaft seals must be working.

    Now for the fun part. Replace the solenoid. Wrap a piece of tie wire once around the end of the hairpin. The hairpin should slide out of the loop easily. Then run the end of the tie wire thru the hole between the end of the hairpin and the tie wire so that the hairpin is held in place. Pulling the end of the tie wire out of the hole will allow the tie wire to release from the hairpin later. With the hairpin dangling from the tie wire you can get the end of the hairpin started in the hairpin slot and get a finger on the end of the hairpin, then pull the end of the tie wire out of the hairpin and the tie wire will come loose. Use a gentle push on the end of the hairpin to install it and confirm the installation with a mirror.

    Reassemble the car and add just over a quart of new transmission fluid.
    Scarabeo500GT likes this.

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  3. #2
    mdmbaby is offline Cadillac Owners Member
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    Re: Malfunction Indicator Light with P0741 and P1860

    This is great information and much appreciated. Can you please provide a photo or drawing of the hairpin and tie wire that you describe? I'm not sure what you mean by the 'hole', pulling the tie wire and then releasing it from the hairpin. Here is a drawing with a retaining clip which is what you might be referring to as a 'hairpin':


    Thanks again for the post and information.
    Attached Images

  4. #3
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Here are the photos that you requested. I used a piece of white electrical wire to simulate the hair pin, retaining clip, or as it is called in the solenoid installation instruction sheet 'spring-clip'. You will need to bend the wire a little different to get the spring-clip into position. I bent them for clarity of the photos. I used 16 gauge tie wire, but any wire that is bendable and stiff enough to hold its shape will work.

    I have been wondering if anyone else will use the method. It is a lot easier than pulling the transaxle.
    Attached Images

  5. #4
    mdmbaby is offline Cadillac Owners Member
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    Re: Malfunction Indicator Light with P0741 and P1860

    Thanks for the photos.

    I found a place that will do a full service on the transmission and replace the solenoid and neutral switch, filter and fluid for $800. He said that on a '99 Deville, you have to drop the transmission which means taking out the front end bracket, etc. More work than I'm willing to do and for that price, it's only about $700 more than the parts alone.

  6. #5
    Domino1968's Avatar
    Domino1968 is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Great tip 2001 Seville SLS!!! Your method sounds very do-able. I have a few questions about your procedure:
    1. How much clearance did you have after cracking open the transaxle case?
    *I am assuming not to much if you are saying just enough to get one finger in, i hope it might be more like two fingers.
    2. About how long did it take you to complete the whole job?
    3. Also, how long did it take you to put the pin back in?

  7. #6
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    The clearance you will have is the clearance between the side cover and the sheet metal at the inner fender. I used a bent o-ring pick to remove the clip and it fell to the bottom where I could retrieve it. A PITA. Use the wire or a long bent needle nose to control the pin when you remove it. I can remember touching the pin with a from each hand.

    I did the whole job on a Saturday. I spent a lot of time trying to get the spring-clip back in before regrouping, taking a break, and out-thinking the clip. Your time will be spent removing the side cover and the things in the way of the removing side cover.

    It took less than a minute to install the clip using the wire. After having fought it for an hour or two before regrouping, it was too easy.

  8. #7
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    1. The clearance you see between the side cover and the inner wheel fender is the clearance you will have.

    2. I did the whole job on a Saturday. It took me longer because I spent a significant amount of time trying to get the spring-clip back in before I took a break, regrouped and came up with the wire method. It think it will take about four hours to do the job again.

    3. It took less than a minute to install the spring-clip using the wire.

  9. #8
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Here is some additional information to add to the following sections in post one.

    PROBLEM:

    Do not use this procedure if you have P0741 but P1860 is not present. P1860 tests the electrical circuit. P0741 tests an expected response in the hydralic circuit that may or may not be caused by a bad TCC PWM Solenoid. If P1860 is not present then the electric circuit which includes the TCC solenoid is almost certainly ok.

    When P0741 is the primary cause the vehicle may be experiencing additional symptoms such as surge or chuggle. This is a different problem that is described in the GM service bulletin, Subject: Service Engine Soon (SES) Light On, Diagnostic Trouble Code (DTC) P0741, Torque Converter Clutch (TCC) Excessive Slip, Transaxle Chuggle, Slip/Surge (Inspect/Replace Internal Transaxle Components) #04-07-30-034 - (08/06/2004)

    See the thread: http://www.cadillacforums.com/forums...60-1998-a.html


    TROUBLESHOOT:

    Step 3.1 Verify that the TCC switch at the brake pedal is operating correctly. It switches a B+ power signal form IGN 1 fuse to both the TCC and Cruise Control. Test the switch by verifying that pressing the brake pedal will release the cruise control. A loose switch can bounce around and cause the TCC Solenoid to engage and and disengage randomly.

    Step 3.2 Test the circuit from the switch to the PCM by checking voltage at PCM C2, terminal 80. With the ignition ON but not running there should be B+ voltage that turns off when the brake pedal is pressed. The B+ signal must be present to allow the TCC Solenoid to engage.

  10. #9
    mitchjagger's Avatar
    mitchjagger is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Did you have to remove the transmission fluid cooler lines or the coolant reservoir?

  11. #10
    ibm4mad is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    I have not done this procedure yet (still debating it) but one tool that may be of assistance is an extra-extra long pair of needle nose pliers. They are somewhat inconvenient to come by because not every auto part store / hardware store will have them but I got a pair with long "tongs' --- gosh, the actual metal "needle noses" were almost a foot long. Makes it easy and great to grip things down long distances. Great to have around the shop for when you drop bolts in tough or hot places.

  12. #11
    Marco is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Is this method feasible on the 00-05 Deville? IOW, is it the same amount of room(or lack of it) in which to work?

    Anyone here done it w/o dropping the engine?




    2000 base deville

  13. #12
    Master Loafer is offline Cadillac Owners Member
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    Re: Malfunction Indicator Light with P0741 and P1860

    Quote Originally Posted by mitchjagger View Post
    Did you have to remove the transmission fluid cooler lines or the coolant reservoir?

    I am having this same problem now. I posted a little over a month ago about having transmission fluid in my radiator and when I replaced it and was having the engine flushed, they found they needed to flush transmission also. I verified this by seeing the milky tranny fluid. They flushed everything and even removed transmission pan to clear the filters/strainers, whatever you call them... ... When my boss (a former Ford certified mechanic) hooked up his diagnostic thing and found these 2 codes about 2 weeks after I had the above work done. One of them said (Pending) ???? Don't remember which code. I will get him to run it again Sunday night at work and let you peeps know. I do know now that my overdrive is gone. I used to run 2000 RPM at 70MPH... now its 2000 RPM at around 50MPH which makes my drive to work boring. I work 38 miles away (ONE WAY)...

  14. #13
    SliceOfLife is offline Cadillac Owners Enthusiast
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    Re: Malfunction Indicator Light with P0741 and P1860

    Quote Originally Posted by 2001_Seville_SLS View Post
    1. The clearance you see between the side cover and the inner wheel fender is the clearance you will have.

    2. I did the whole job on a Saturday. It took me longer because I spent a significant amount of time trying to get the spring-clip back in before I took a break, regrouped and came up with the wire method. It think it will take about four hours to do the job again.

    3. It took less than a minute to install the spring-clip using the wire.
    What about the side cover gasket? Does the side cover come off enought to replace the gasket if necessary? Was it necessary to replace the gasket when you did it?

  15. #14
    2001_Seville_SLS is offline Cadillac Owners Fanatic
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    Re: Malfunction Indicator Light with P0741 and P1860

    Slice of Life,
    I used the original side cover gasket and torqued the bolts to specs in three phases. There were no leaks. It is possible to change the gasket if required, but I would just take care not to damage the old one if I did it again.


    Mitchjagger,
    I removed the fluid reservoir, but don't remember messing with any transmission fluid lines.


    Marco,
    I didn't drop the engine. There has been at least one other guy who has performed the procedure. If my memory is right, I think it was on a Deville.

  16. #15
    Master Loafer is offline Cadillac Owners Member
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    Re: Malfunction Indicator Light with P0741 and P1860

    I just typed you a 500 word PM and it wouldn't let me send it....LOL.... Anyways, if you could contact me via email, I have a question about my 2001 Deville. It is giving out the same codes. email is :simsters@sbcglobal.net
    .
    .
    I have a question about the road testing part. Thanks !
    .
    .
    If I don't hear from you, I will post a thread with my story and maybe you peeps can help me out there. I am off this week and need to fix my car.
    .
    .
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    Thanks for any and all help !

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