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High Idle and TCC code


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My car acquired 2 new issues yesterday. To start at the beginning and with the first issue, I was driving home from the store and was stuck behind someone going 20mph in a 45 zone, so I gave it a bit of gas to pass him (not sure if this has ANY relevance at all to the problem). When I got home and put the car in PARK, the idle went up to 2,000 and stayed there. I tried revving the gas a little to drop it back down, but to no avail. This high idle is now happening EVERY time the car is in park, but now it's fluctuating at a steady "pulse" from 1,000 to 2,000, then back down to 1,000 again. Nothing I do makes it drop to normal, so I have to time my shifting into gear to when the idle is at its lowest point (1,000rpm's). This ONLY happens when the car is in park. As soon as it's put into any other gear the idle drops to normal. The ISC motor was cleaned and adjusted a couple months ago, I cleaned the throttle body again today, and there are no codes set except for P039. What else can cause a high idle in park?

Onto the 2nd issue. I have been dealing with an intermittent code P039- TCC/VCC engagement problem, for a few months now. It normally only sets at 45mph. Well, twice now since yesterday it set when I was driving only 20mph. Could this mean the problem is getting worse? It still seems to be shifting fine through all gears. No jerking or lag.

Thanks ahead of time for any info or advice.

It's a 1994 eldorado.

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I have had the same problem with the P039 code on the 93 Eldo for some time. The setting on the P039 code seems to getting set more frequiently and at lower speeds. There appears to be no effect on the shifting of the trans. On the down side you loose torque converter lock up and this wastes about 10% of your mpg while driving at speeds greater than 45 mph.

Edited by BSchlossmann
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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

The saddest thing in life is wasted talent

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

I kinda thought so, but wasn't 100% sure. The only other thing I can think of is the TPS, but it seems that would throw a code and it wouldn't be happening just in park. My original thought was that is was the ISC again, but it's not acting the same as it was when that was the problem before.

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

I kinda thought so, but wasn't 100% sure. The only other thing I can think of is the TPS, but it seems that would throw a code and it wouldn't be happening just in park. My original thought was that is was the ISC again, but it's not acting the same as it was when that was the problem before.You can test the TPS with an ohmmetr. There should be no jumps in resistance when you move the throttle. Could be also ECM (PCM)problem.

The saddest thing in life is wasted talent

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

I kinda thought so, but wasn't 100% sure. The only other thing I can think of is the TPS, but it seems that would throw a code and it wouldn't be happening just in park. My original thought was that is was the ISC again, but it's not acting the same as it was when that was the problem before.

You can test the TPS with an ohmmetr. There should be no jumps in resistance when you move the throttle. Could be also ECM (PCM)problem.

The saddest thing in life is wasted talent

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

I kinda thought so, but wasn't 100% sure. The only other thing I can think of is the TPS, but it seems that would throw a code and it wouldn't be happening just in park. My original thought was that is was the ISC again, but it's not acting the same as it was when that was the problem before.

You can test the TPS with an ohmmetr. There should be no jumps in resistance when you move the throttle. Could be also ECM (PCM)problem.

A friend of mine told me it could be the PCM....I'm really hoping that isn't my case.

Just for the heck of it, I ran a CarFax report on my car, and according to that the PCM was checked by a dealer in 2004, so I'm wondering if it has had prior problems with it. Also, as far as the transmission goes, it says that was flushed and checked in 2005 by a dealer (though I find it odd that the fluid was overfilled when I bought it and there is a service receipt stating the fluid was changed again not long ago...though that doesn't appear on the CarFax). From what the CarFax report says this car was dealer-maintained up until 2007. After that it just says "service facility" for anything else that was done on it.

I know I need to get this high idle thing figured out. It's making it really hard to put the car in gear without slamming the transmission.... Do you know what the reading on the TPS should be?

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This high idle is now happening EVERY time the car is in park, but now it's fluctuating at a steady "pulse" from 1,000 to 2,000, then back down to 1,000 again.

That sounds a lot like a vacuum leak to me.

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I know it burns more gas because it isn't going into overdrive as it should, but what I'm wondering is this: Is the fact that the code is setting sooner and more often a sign that my transmission is in danger? What is the worst-case scenario if I ignore this code and it keeps setting?

Another question, I know that when I had the high idle before it was suggested that a clogged EGR valve could have been to blame. At that point though the idle was high all the time. Could that also be a possibility in this case since it is ONLY doing it in park now?

EGR is disabled in park. Can't say what's going on though...

I kinda thought so, but wasn't 100% sure. The only other thing I can think of is the TPS, but it seems that would throw a code and it wouldn't be happening just in park. My original thought was that is was the ISC again, but it's not acting the same as it was when that was the problem before.

You can test the TPS with an ohmmetr. There should be no jumps in resistance when you move the throttle. Could be also ECM (PCM)problem.

A friend of mine told me it could be the PCM....I'm really hoping that isn't my case.

Just for the heck of it, I ran a CarFax report on my car, and according to that the PCM was checked by a dealer in 2004, so I'm wondering if it has had prior problems with it. Also, as far as the transmission goes, it says that was flushed and checked in 2005 by a dealer (though I find it odd that the fluid was overfilled when I bought it and there is a service receipt stating the fluid was changed again not long ago...though that doesn't appear on the CarFax). From what the CarFax report says this car was dealer-maintained up until 2007. After that it just says "service facility" for anything else that was done on it.

I know I need to get this high idle thing figured out. It's making it really hard to put the car in gear without slamming the transmission.... Do you know what the reading on the TPS should be?

Carla, you'll be lucky if it is indeed the PCM. A refurbished one should be around $100 at Advance and it is easy to replace. I do not know what are the reading of the TPS on Northstar. I would just make sure it is smooth over all the range.

I would remove the glove box to get access to the PCM and tap on it with something to see if it makes difference when the car is acting up. Just a suggestion, cannot really say what's going on.

The saddest thing in life is wasted talent

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EGR is disabled in park. Can't say what's going on though...

I didn't know the EGR was supposed to be disabled in PARK. What would happen if it were NOT being properly disabled?

Regards,

Warren

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EGR is disabled in park. Can't say what's going on though...

I didn't know the EGR was supposed to be disabled in PARK. What would happen if it were NOT being properly disabled?

Regards,

Warren

If EGR is open at low RPM (Park) the engine may stall. I do not see how faulty EGR system could cause that high idle in park. I still think rather a faulty PCM might be the culprit.

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At this point, I would suspect the ISC motor closed throttle switch. You stated you cleaned it but it could be corroded again and not making contact. If the closed throttle switch is not making proper contact, the idle will fluctuate.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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At this point, I would suspect the ISC motor closed throttle switch. You stated you cleaned it but it could be corroded again and not making contact. If the closed throttle switch is not making proper contact, the idle will fluctuate.

I do realize that, and that was my first thought but as I said the idle problem is different now then it was when the ISC was to blame. Also, it was just taken apart, cleaned, and adjusted in late Jan-early Feb so I find it unlikely to have corroded again that quickly. I may be wrong.

I went out this morning after getting my son on the bus to check for vacuum leaks or anything else visible/obvious. I only found one thing that concerned me at all, and I'll try my best to explain what I am talking about. I have previously seen my brother push in on the diaphragm the throttle cable hooks to (I believe it's the cruise control diaphragm? Not entirely sure) and any time he has pushed on it before, it would rev the engine. Well, I pushed on it when I was out there this morning and it didn't do anything at all, so I'm wondering if there may be something wrong with the cruise control? Or possibly the throttle cable sticking? It seems to me though that the idle would be up all the time if that was the case. I'm going to stop by my brother's work in a couple hours and have him take a look at it and see what he thinks. I'll post whatever is found, if anything. If nothing can be found wrong there, then I will look into the possibility of a PCM issue. I still find it odd that it's not setting any codes at all....

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

Excessive humidity can affect electrical connection. I would check at least all the accessible grounds.

The saddest thing in life is wasted talent

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

Excessive humidity can affect electrical connection. I would check at least all the accessible grounds.

Will do. Also will check the TPS with an ohm meter and see how that looks. It's supposed to rain tomorrow but I'm really hoping it holds off long enough for me to check a few things out.

Could a bad ground really cause a high idle? If so, I was completely unaware of that.

You learn something new every day...especially when you own a cadillac. biggrin.gif

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

Excessive humidity can affect electrical connection. I would check at least all the accessible grounds.

Will do. Also will check the TPS with an ohm meter and see how that looks. It's supposed to rain tomorrow but I'm really hoping it holds off long enough for me to check a few things out.

Could a bad ground really cause a high idle? If so, I was completely unaware of that.

You learn something new every day...especially when you own a cadillac. biggrin.gif

A bad ground can affect PCM and consequently idle. As for learning something new every day... high idle IN PARK...that's new to me! lol

The saddest thing in life is wasted talent

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

Excessive humidity can affect electrical connection. I would check at least all the accessible grounds.

Will do. Also will check the TPS with an ohm meter and see how that looks. It's supposed to rain tomorrow but I'm really hoping it holds off long enough for me to check a few things out.

Could a bad ground really cause a high idle? If so, I was completely unaware of that.

You learn something new every day...especially when you own a cadillac. biggrin.gif

A bad ground can affect PCM and consequently idle. as for learning something new every day... high idle IN PARK...that's new to me! lol

I find it strange too! Any other case of a high idle that I have ever heard of involved it happening in any/every gear...not just park. That's part of why I was at such a loss as to where to start looking for the cause....

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Unfortunately, my brother couldn't get my car into the garage today because he was swamped at work. I did notice something strange though . When I left earlier to run some errands, it was pouring rain, and the idle was perfectly fine the whole time I was out and about with the car. By the time my boyfriend left for work, the rain had stopped, the sun was out and almost everything was dry and when he started the car the idle was acting up again. Maybe it's just a coincidence, but does anyone else think it's a little strange that the one time it's raining since the idle started acting up, it runs perfect? There hasn't been a single time in the last few days that the car has idled right in park, and it has been dry out except for earlier today.

Excessive humidity can affect electrical connection. I would check at least all the accessible grounds.

Will do. Also will check the TPS with an ohm meter and see how that looks. It's supposed to rain tomorrow but I'm really hoping it holds off long enough for me to check a few things out.

Could a bad ground really cause a high idle? If so, I was completely unaware of that.

You learn something new every day...especially when you own a cadillac. biggrin.gif

A bad ground can affect PCM and consequently idle. as for learning something new every day... high idle IN PARK...that's new to me! lol

I find it strange too! Any other case of a high idle that I have ever heard of involved it happening in any/every gear...not just park. That's part of why I was at such a loss as to where to start looking for the cause....

Have you tried to kick the PCM (gently)?

The saddest thing in life is wasted talent

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I haven't tried kicking or tapping it, no, though I've contemplated kicking the car in general on several occasions....mellow.gif I would never do that though.

It's pouring rain again today, and I have to go a couple places later, so I will see if the idle still acts up or if it runs fine again. If it does act up, I'll kick or knock on the PCM to see if it changes anything. I hate that I have a very limited amount of time to do anything with/to it during the week so most things have to wait until the weekend.... I want to check the TPS and the grounds but I'm not thinking that's a great idea in the pouring rain.

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just for the hell of it If you can access a scantool, I would see if the Coolant temp sensor is reading properly, It is very possible it is raising the idle because the CTS may be shorted

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just for the hell of it If you can access a scantool, I would see if the Coolant temp sensor is reading properly, It is very possible it is raising the idle because the CTS may be shorted

I had that thought too honestly, that maybe the car "thought" it was cold and was raising the idle, like it does when you start it in the winter. The CTS was replaced about a year ago though, and my temp gauge still reads perfectly. I doubt that's the issue, but I do want to get my brother to hook a scan tool to it to see if there is anything that may show up on that since I still am not getting any codes in the car at all.

As of yesterday, the high idle is no longer only happening in PARK. It seems sporadic, and there doesn't appear to be a pattern to it. Sometimes it will idle fine in park now, other times it doesn't. I came home from the store yesterday and didn't even have to touch the gas pedal almost all the way home. It got up to 30mph ON ITS OWN! It's also fighting me when I have to use the brakes as it's still trying to go. NOW it is acting like it did when the ISC was having problems except that then, it was CONSTANT, and now it's INTERMITTENT, so I think my next step is going to be to take it apart AGAIN and try to clean/adjust it. If that doesn't work then I may try replacing it all together (not wanting to do that as it is an expensive part). If anyone else has any other suggestions to offer, I am open to any ideas.

I don't have an ohm meter handy, so I am going to use the OBD to monitor the TPS a little later today and see if that seems abnormal at all. Also, I did try kicking (gently) and tapping on the PCM when the idle was up, and it didn't change anything.

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just for the hell of it If you can access a scantool, I would see if the Coolant temp sensor is reading properly, It is very possible it is raising the idle because the CTS may be shorted

I had that thought too honestly, that maybe the car "thought" it was cold and was raising the idle, like it does when you start it in the winter. The CTS was replaced about a year ago though, and my temp gauge still reads perfectly. I doubt that's the issue, but I do want to get my brother to hook a scan tool to it to see if there is anything that may show up on that since I still am not getting any codes in the car at all.

As of yesterday, the high idle is no longer only happening in PARK. It seems sporadic, and there doesn't appear to be a pattern to it. Sometimes it will idle fine in park now, other times it doesn't. I came home from the store yesterday and didn't even have to touch the gas pedal almost all the way home. It got up to 30mph ON ITS OWN! It's also fighting me when I have to use the brakes as it's still trying to go. NOW it is acting like it did when the ISC was having problems except that then, it was CONSTANT, and now it's INTERMITTENT, so I think my next step is going to be to take it apart AGAIN and try to clean/adjust it. If that doesn't work then I may try replacing it all together (not wanting to do that as it is an expensive part). If anyone else has any other suggestions to offer, I am open to any ideas.

I don't have an ohm meter handy, so I am going to use the OBD to monitor the TPS a little later today and see if that seems abnormal at all. Also, I did try kicking (gently) and tapping on the PCM when the idle was up, and it didn't change anything.

Carla, I have got an impression that the previous owner experienced most of the symptoms you have been describing, replaced several parts (just like everybody would do), flushed transmission, etc., did not find the problem, and sold the car. Electrical issues have been driving me nuts for two last years of owing my 1991 Seville.

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