I have a code 27 on an 84 SDV
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 4 of 4
Like Tree1Likes
  • 1 Post By carnut
HT4100 4.1, 4.5, 4.9 Discussion, I have a code 27 on an 84 SDV in Cadillac Engine Technical Discussion; Code 26 is a shorted TPS. I checked the TPS itself and all was fine. I back traced the wire ...
  1. #1
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,890

    I have a code 26 on an 84 SDV

    Code 26
    is a shorted TPS. I checked the TPS itself and all was fine. I back traced the wire harness to it and discovered that a wire behind the idle control motor harness was pinched under the A/C compressor bracket! I pulled the wire out and taped up the bare spot. Now that enabled me to erase the code, but at any RPM above curb idle that code reappears. My manual says if no short I have a damaged ECM. I think the pinched, shorted wire damaged that circuit in the ECM and will require ECM replacement. If I raise the throttle to clear the idle speed motor, the motor shaft retracts until it virtually bottoms out. Allowing the car to run at idle, eventually the shaft on the idle control motor extends out to compensate for the compressor load. I cannt press and retract the shaft to get the gap adjustment. Would you agree, I need an ECM?

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,890

    Re: I have a code 27 on an 84 SDV

    My mistake! Code 26

  4. #3
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): 2011 Crown Vic LX
    Join Date
    Oct 2004
    Location
    Oak Creek, WI
    Posts
    5,313

    Re: I have a code 27 on an 84 SDV

    Code 26 is a shorted throttle switch, not TPS. Don't confuse it with the TPS - which would throw a code 21 if shorted.

    The throttle switch is located inside the ISC. The switch's job is to tell the computer when you are off the throttle, so that the computer knows its time to idle the engine. The switch closes when the throttle hammer contacts the ISC shaft. That's why you are experiencing odd ISC operation with this code. When you raise the RPM's, the computer still thinks you are off the throttle due to the shorted switch - therefore it continues to try to lower the RPM by retracting the shaft. I would assume the code sets because as it retracts the ISC, it doesn't see the TPS angle or RPM change accordingly.

    Sometimes, you can disassemble the ISC and clean the switch. Else, you'll need to replace it.

  5. #4
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,890

    Re: I have a code 27 on an 84 SDV

    THANK YOU!!!! Couldn't see the forest for the trees! will be replacing the ISC Monday.
    drewsdeville likes this.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting