Question about Cadillac Eldorado

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1995 cadillac eldorado . Idle surging . Replaced the TPS ,The Isc . PCM replaced a year ago. No current obd1 codes . Pd codes all normal parameters ranges. pcm supposed to alternate +to-

This happens when pcm warms up and goes from open loop to closed loop . I think an electronic component is bad as it is intermittent some times idles properly at 700rpm

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Surging idle is almost always caused by a vacuum leak, not an electrical issue.

Posted on Jan 20, 2019


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Posted on Jan 02, 2017

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SOURCE: OBD 1 and 2 will not communicate with PCM.

a blown fuse will also cause the obd to not communicate

Posted on Nov 12, 2008

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SOURCE: ECM switches from closed loop to open loop at idle after warmup


Posted on Sep 30, 2009

  • 85 Answers

SOURCE: Idle on my 1992 cadillac deville is very low

no take that ****** out and give it a bath in carb cleaner 20 mins coat with wd 40 reinstall if its better by a new one any way only a temporary fix dont////dont turn any screws

Posted on Jan 28, 2010

  • 171 Answers

SOURCE: i have a 1997 rav4..4cyl stalls when taking off

Since you are not getting any codes , I think your problem may be in the fuel system.Have you checked the fuel pressure / regulator? Or any voltage drop in the system.

Posted on Mar 08, 2010

  • 335 Answers

SOURCE: 1987 Full Size Ford Bronco

Make sure you have no vacuum leaks and check/replace the Idle Air Control valve, its located on the side of the thottle body.

Posted on Mar 27, 2011

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Hi please tell me what is the code po80 and po52 and p071 and T037 and S030 in cadillac devill 1995

AWH: Cadillac On-Board Diagnostic Trouble Codes (OBD)
Diagnostic Trouble Codes for OBD I equipped General Motors (GMC, ... BCM Codes; ECM Codes; PCM Codes; IPC Codes; ABS Codes; SIR Codes ..... LR Wheel Speed Sensor Frequency Error T037 . ...... Intermittent TPS Signal P071 (E071) . ..... NOTE: The part numbers listed above are for the Cadillac Deville, Eldorado ...

Lightbulb Re: How can I check for any codes Im throwing ... > ... > Past Cadillac Vehicle Discussion

Jan 28, 2004 - 11 posts - ‎8 authors
I heard that if you hold temp and off, it will show you the codes you are throwing. ...Cadillac DeVille 1985 to 2005 including: ... Diagnostic Trouble Codes for OBD I equipped General Motors (GMC, Chevrolet, Buick, Oldsmobile, .... T037 .......... .............................. LR Wheel Speed Sensor Continuity Fault T041 .

Trouble Code Help???? OBD1 Codes, 1993 GM Cadillac El Dorado ... > ... > General Technical Section > General Tech
Nov 30, 2007 - I retrieved these codes : PO31, PO52, PO53, PO91, IO39, IO52, AO48 they had History behind them but Iwant to know what these mean and are ...

Jan 19, 2016 | Cadillac Cars & Trucks

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How do I adjust the throttle position sensor on my 93 cadillac seville sls 4.9l engine?

4.5 And 4.9L Engines
  1. Remove the air cleaner.
  2. Remove the TP sensor connector.
  3. Unscrew the 2 TP sensor attaching screws and retainers, and remove the TP sensor.

To install:
  1. With the throttle valve in the normal closed idle position, install the TP sensor on the throttle body assembly.
  2. Install 2 TP sensor attaching screws with retainers. Do not tighten the screw until the TP sensor is adjusted.
  3. Install the TP Sensor connector. Adjust the TP Sensor and perform the idle learn procedure.
  4. To Perform the TP sensor adjustment.
    1. Disable the generator by grounding the green harness connector plug adjacent to the generator.
    2. Start the engine, enter diagnostics, and select PCM override PS103 'ISC Actuator'
    3. Press the 'COOLER' button on the CCP to retract the ISC Actuator. This action will disengage the A/C compressor and command the EGR 'OFF'. The Climate control center display will change from '50 to 00'. The ISC Actuator will slowly retract (about 20 seconds) to a fully retracted position. Verify that the throttle lever is resting on the minimum idle speed screw. With the ISC Actuator plunger fully retracted, disconnect the ISC harness.
    4. Select the PCM data PD01, 'TP Sensor', while still in PCM override PS03. Note the throttle position (in degrees) displayed on PCM parameter PD01.
    5. (-0.5° TO + 0.5°)

      No TP sensor adjustment required. Reattach the ISC Actuator harness and disconnect the grounding wire at the generator.
    6. TP Sensor (-10.0° TO -0.6°) or TP Sensor (+ 0.6° TO + 90.0°) TP Sensor adjustment required.

  5. With the engine 'OFF' and the ignition 'ON', reenter diagnostics and select PCM override PS03 'ISC Actuator'. Press the 'COOLER' button to retract the ISC Actuator the minimum air setting.
    1. Loosen the TP sensor screws just enough to permit the sensor to be rotated. Open the throttle slightly and allow the throttle lever to snap shut against the minimum air screw. Adjust the TP sensor so the parameter display is 0°. Tighten the TP sensor mounting screws with the sensor in the adjusted position. Recheck the parameter to be sure the TP sensor parameter is (-0.5° to + 0.5).
    2. Install the air cleaner.

Dec 25, 2015 | Cadillac Cars & Trucks

1 Answer

Idle speed is very high most of the time


Check accelerator cable, idle air control system and idle speed control motor(ISC), air intake setting and sensors, check the vacuum system. Scan the PCM for diagnostic trouble codes. ISC, vacuum leaks and air intake problems are the most common cause for fast idle on this car.

Dec 15, 2011 | 1995 Cadillac Seville

1 Answer

My 89 Seville STS started to idle high sometimes but not all the time. Now it seems to be doing it mostly all the time. I just replaced the ISC myself with no change. Is there something else I can...

Yes, there is a procedure to get the engine to idle correctly. Turn engine off, key on Open the throttle and let in snap shut against the minimum air screw. The throttle angle displayed in diagnostics on ECM parameter ED01 TPS -1.0 to + 1.0. The TPS should be adjusted to fall into this parameter. After that has been done. Connect a wire from the -side of battery to terminal c on the isc motor. and a wire to the + side of battery to terminal d. The plunger should be at its highest position against the throttle lever to adjust. This may take a few times of applying power to get it to ratchet to full ext. The TPS parameter should be at 10.5 to 11.5 on the diagnostic center. Adjust by turning the plunger on the ISC. Press the cool blue button and the off button to get the diagnostic function up. Any more question please reply as I have a service manual and fixed my 89 seville for this problem.

Aug 21, 2011 | 1989 Cadillac Seville

1 Answer

My 1995 Eldorado ETC will shut down (intermittent) at idle. All electrical power stops. Car does restart in after a couple of minutes. Battery cables are clean and tight.

You will need to find the codes that the car is getting. You can do this by entering diagnostics on the dash.
1. Turn the ignition switch ON. [Bruce notes: interestingly, the engine can be on or off]
2. On the cars up to 1995, on the Climate Control panel, press the OFF and WARM buttons simultaneously.
  • E -- ECM trouble code
  • P -- PCM trouble code
  • C -- Current trouble code
  • H -- History trouble code
  • NO X CODE -- No code present (X represents the system)
  • NO X DATA -- Communication lines are not operating (X represents the system)

Nov 12, 2010 | 1995 Cadillac Eldorado

1 Answer

I have a 1984 Cadillac Eldorado Biarritz. the service soon light is on so I took it to aamco. they said the throttle swith was the cause for the light (the throttle switch is in the Idle speed control...

Hello: The ISC motor should be adjusted. The part that screws into the larger shaft coming out of the motor should be approximately 17 mm. The code does not have to be cleared for the light to go away. You should collapse the ISC motor and check the tps it shoud be -1 to +1 best at 0. Call me if you need further assistance. I have a 1984 Cadillac service manual. 662-449-7099.

Nov 04, 2010 | 1984 Cadillac Eldorado

3 Answers

Idle at 250 rpm

Idle Speed Control (ISC) Motor OPERATION Eagle Throttle Body Fuel Injection (TBI) System NOTE: The Eagle TBI system is used only on 2.5L Premier engines. The Idle Speed Control (ISC) motor is mounted to the throttle body and controlled by the PCM. The throttle lever rests against the initial adjustment screw of the actuator (plunger). The idle speed is not adjustable. The initial adjustment screw is only used to establish the initial positioning of the actuator when the ISC motor has been replaced. The actuator extends or retracts to control engine idle speed and to set throttle stop angle during deceleration. Based on inputs from the various engine control system sensors and switches to the PCM supplies current to the ISC motor to adjust the actuator position for the particular operating conditions.

Aug 05, 2010 | 1995 Dodge Spirit

1 Answer

What does the code po85 mean for a 1994 cadillac deville

It means that the throttle body is dirty and the deposits in the throttle bores are restricting air flow at idle to the point that the idle speed control has no more authority to maintain the correct idle speed.

Take the air cleaner off, hold the throttle wide open and look down the throttle bores. Spray the throttle bores with carb cleaner and scrub the bores and backside of the throttle blades with an old toothbrush. Cleaning the deposits off the bores and throttle blade backsides it will restore the idle air flow to the correct level. When the throttle body is clean, disconnect the battery negative cable for 60 seconds to reset the idle learn offsets to the "clean throttle body" default values.

While you are in the throttle body and looking down the bores....see the two tubes sticking up at you from the intake manifold floor just below the throttle blades...??? Those are the EGR tubes and they are NOT supposed to be full of carbon and crud. Rod them out thoroughly with a piece of stiff wire to remove the deposits. Go all the way down thru the tubes to the cast passage below and make sure that they are clean and unrestricted so that the proper amount of EGR can flow.

Turning the key to the run position extends the ISC anticipating a restart, so if the setting is incorrect it would not erase a hard code. Just turning the key to run would light up both the service soon and service now lights as a bulb check, in other words, letting you know the bulbs work. Do you have the factory service manual?

The ISC adjustment is simple on this car. With the engine running and at operating temperature, You raise the throttle arm slightly with your right hand and push the shaft of the ISC in to fully retract it with your left hand. With constant pressure on the ISC shaft it will slowly retract. The very second it bottoms, you quickly remove the wiring connector to the ISC. Now you should have a very low idle and a gap between the throttle arm and the tip of the ISC. Approx. 0.060 of an inch. Once you know the gap is correct, shut off the engine, wait 10 seconds and reconnect the ISC wiring. Restart the engine and the ISC is set to spec. The TPS setting must be verified at this time. At minimum idle, ISC not touching the throttle arm, and unplugged, the TPS should be reading approx .0 or .1. Once the ISC is reconnected, you should see a TPS reading of approx. .5 at idle. with the A/C off.

A hard code can be erased but will continue to reset as long as the reason for it has not been corrected. Idle learn procedures were designed into later year engines with multi port fuel injection to adjust idle regardless of the amount of coke build up within the throttle body. Your fuel injection system does not build up coke or deposits because the 2 injectors spray down thru the throttle body, effectively cleaning the throttle body while running. Alot of owners adjust the ISC as if it were a throttle stop screw on a carb. guessing as they go. The ISC and TPS "MUST" be in sync to get the best off throttle response and smoothest idle. Adjusting the ISC without verifying gap or TPS voltage usually results in a surging or too high warm idle. You say the car failed at idle. For what reason? CO or HC? or idle too high?

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Jul 20, 2010 | 1994 Cadillac DeVille

3 Answers

1989 cady 4.5 liter car idle high until car warms up.maybe 15 minutes or 5 miles of driving

This is not normal for this car. Sholly-NG is WRONG..!!! The TPS sensor needs to be at its proper setting. It must be set at -1.0 to +1.0 on the diagnosatics center on ECM parameter ED01 TPS with key on and motor off and throttle shut against the air screw or stop. I moved the ISC "idle speed control' out of the way to get this setting {mine is -1.0 } Now with the ISC back in place it must be fully extended with the use of a jumper wire by - to terminal c and + to terminal d. Now with it at maximum extension the TPS parameter should be 10.5 to 11.5 . To adjust it correctly you will need to turn the plunger in to lower the parameter and out to increase. Setting the TPS will increase you gas mileage and correct the idle problem. This is not a job that just any parts replacer can do. You must follow these steps to fix it correctly.

Jan 22, 2010 | 1989 Cadillac Seville

1 Answer

1995 Cadillac Eldorado

Sounds like the ISC motor ratcheting. Either is out of adjustment or faulty. ISC and TPS must be set correctly together with each other. Hope this helps

May 02, 2009 | 1995 Cadillac Eldorado

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