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03 CTS 3.2L Engine Idles Rough


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Ok....today my wife calls and says the screen that shows the radio channel which is also the screen that i was able to get the error messages from by pressing f1 and f6......

I found it odd that the computer just offered up this information without any promps.....

......SERVICE IDLE CONTROL.......

press clr to continue

The new error codes are:

PO507C Incorrect idle speed

B3832H Window position

B2470C Cell phone

B2365H........which i cannot find on the list and it will not go away......

The engine light has also come on.........

Any thoughts?

Where is the idle control??

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Not a direct response, but here is the idle learn procedure for the 2003 CTS:

Idle Learn Procedure

The engine control learns the idle position of the throttle body for correct operation. When the throttle body or ECM is replaced, this procedure must be performed to ensure correct idle operation. The engine idle may be unstable or a DTC may set if the idle position has not been learned. Perform the following procedure in order to allow the ECM to learn the idle position:

1. Ensure that the following conditions are met:

* The vehicle speed is 0 mph.

* The accelerator pedal angle is less than 14.9 percent.

* The battery voltage is more than 10 volts.

* The engine coolant temperature (ECT) is between 5-60°C (41-140°F).

* The intake air temperature (IAT) is between 5-60°C (41-140°F).

2. Turn OFF the ignition for 30 seconds.

3. Turn ON the ignition, with the engine OFF for 1 minute.

4. Turn OFF the ignition.

5. Turn ON the ignition, clear codes if required.

Bruce

2023 Cadillac CT4-V Blackwing

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Any thoughts?

Where is the idle control??

Without a FSM for your car, I have no clue. I would guess that it is either an ISC motor externally mounted in contact with the throttle linkage or more likely an IAC valve mounted on the side of the TB that controls bypass idle air.

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  • 1 year later...

Hello, ....well im going on 2 years now with this slow/rough idling caddy.

I have it up for sale and know the first person who comes to drive it is going to not buy it due to the slow idle.

I spoke with the 5th place today and have no confidence in this guy either.

I removed and cleaned the IAC

Did the idle learn procedure

Replaced the plugs

Both coil packs

Checked for vaccuum leaks etc.

The car just idles too slow, when you just slightly touch the accelerator its smooth and no vibration.roughness!

The rpm gage shows id idling at around 500..at 600/650 its perfect.

When you tunr the air on its even worse.

the car has 114,000 miles, V6

Thanks again as this is really a problem for me!!!

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The P2107 tells me that the IAC stepper motor is likely shorted out inside. I don't have a FSM for the 2003 CTS but there should be a resistance check for the IAC. That is probably causing your P0507 and the MIL coming on.

CTS-V_LateralGs_6-2018_tiny.jpg
-- 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.

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At some point you said:

A friend told me to clean the throttle plate he called it.

Wow......did that make a difference.

No rough slow idle now.

Was idle around 500 to 600 rpm now 800 to 1100 rpm....no miss

Did you ever fix the ranging/varying idling after the above?

Jim mentioned this >> The P2107 tells me that the IAC stepper motor << what was the result of your testing?

Personally, you have been asking 5 mechanics and friends and this board, I would just take it to Cadillac and get it fixed right so you can sell it.

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

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Oh C'mon...do you really think i didnt take it there first???????

I did that the very first day, ..all they said was the car has a history of misfires and told me to change the plugs.

All the mechanics around here even at cadillac dealers are kids/idiots.........this is not a simple problem to fix or it would have been fixed a long time ago!

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It does sound like the advice you got was something out of the 1950's. The car has a miss, so change the plugs. I feel your pain.

Sometimes you need to find another Cadillac dealer for a difficult problem. Call a couple of dealerships in a larger town, or one that is larger and does sells lots of Cadillacs. Ask for the Service Manager (this is not one of the Service Representatives that deal with the Service customers, this is their boss) and ask how many techs there are Goodwrench certified on the Tech II. If you don't get a quick, clear answer, thank him/her politely and call another dealer.

Another solution that may be more satisfactory to some of the techs and DIY people here, but not necessarily to you, is to get a copy of the Factory Shop Manual (FSM) for your car, look up the tech's instructions for the P2107 code, and fix it yourself. At $150 to $200 for the FSM, that's probably your quickest, least expensive, and most satisfactory solution, if you are comfortable doing that.

CTS-V_LateralGs_6-2018_tiny.jpg
-- 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.

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Oh C'mon...do you really think i didnt take it there first???????

I did that the very first day, ..all they said was the car has a history of misfires and told me to change the plugs.

All the mechanics around here even at cadillac dealers are kids/idiots.........this is not a simple problem to fix or it would have been fixed a long time ago!

Something sounds wrong with this

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

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I did the idle learn procedure again today.

After doing it the car showed it idles at 1100 rpm...fast and no miss.

It seems it doesnt knoe the correct idle, it also wont keep the idle it sets.

Seems to loose its memory??

Not sure if this helps anyone determine anything that hasnt already been discussed but thought i would throw that in.

thanks agaon for all your help, we already have a 2008 STS and we love it, now we just need to get the 03 into a new home......

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The symptoms you are describing would be caused by the code you are getting

P2107

That code must be run down and solved, check its connections

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

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Like Mike said...the throttle / idle problem is caused by the P2107 code.

It is related to the throttle actuator.

Fix whatever is causing that code...and your idle problem is fixed.

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That code hasnt showed back up for over a year........

Still think that would be the problem?

What codes does it have ...NOW...

Post them and we will go from there.

It can be fixed. :D:D:D

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Current code:

B2470 Daytime Running Lamps Fault

History codes:

U1000 Class 2 Communication Malfunction (there is no U0100 in my list)

B1004 Keep Alive Memory (KAM)

U1714 Loss of Front Door Module to Window Motor Normal Speed Comm.

B3832 Window Position Sensor Circuit

B1826 Something with the lumbar or recline sensor on the driver's seat

B2356 Something with a seat position sensor on the driver's seat

CTS-V_LateralGs_6-2018_tiny.jpg
-- 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.

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None of these codes are an indicator of my problem?? Correct?

I have been getting a rough idle and then it goes away. I know you have coil packs (I believe), have you checked your coil packs? I would pull them, and check their connection at the plugs to make sure they make a good connection and that there is no corrosion or burning of the contacts...

I pulled my ignition wires out of my coils and 4 of the wire contacts were burned and corroded, I cleaned them good with a round wire brush, tightened the contacts and used a little dielectric grease (there are NON AC Delco wires from the prior owner) and the idle is smooth as silk.... It does not appear that I have this miss anymore.

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

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I copied and pasted from above:

I removed and cleaned the IAC

Did the idle learn procedure

Replaced the plugs

Replaced Both coil packs

Checked for vaccuum leaks etc.

I think i have replaced as many items i new to do.....

thanks for your idea.......

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The logical thing to do is to look at the codes that appeared overnight and fix any problems that they tell you about. I think that there are too many codes in just one day to say that the car is healthy. Most of them seem to indicate a problem with a ground or other circuit common to the driver's seat area, with the notable exception of the running lights circuit, which is a current code. A car in good condition will throw a network code or a seat adjustment sensor code or some such every few weeks, but throwing six codes overnight is startling. And, a healthy car will not keep codes current. Thus the first thing to do is to fix the problem indicated by the codes the day after you cleared them.

Check the running lights. One of them may be broken and the bulb shorted, throwing the B2470 code. It may be that a short in that circuit would drag down the voltages in another circuit such as the one for the driver's seat. If you fix a running light bulb and clear the codes, perhaps none of the codes that you saw this morning will come back.

You had a P2107 earlier. This code means that either the circuit to the IAC motor had a problem, the connector had a problem, or that there is an electrical problem with the IAC itself. That, as more than one of us has said, is the likely clue to solving your idle problem. If it comes back, particularly if it is Current, then the first thing I would do is to a resistance check on the IAC. In fact, a resistance check on a stepper motor is so simple, I would do it immediately just to know that the IAC motor looks OK to an ohmmeter.

CTS-V_LateralGs_6-2018_tiny.jpg
-- 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.

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