High Idle and TCC code

[CarlaValentine]

A CTS is a Catera Touring Sedan. I think you mean ECT (Engine Coolant Temperature) sensor. That's what the FSM calls it.

Lol, yeah that. CTS - Coolant Temp Sensor. It made sense to me, but now seeing ECT I remember that as being the right abreviation. At least you knew what I was talking about.

[CarlaValentine]

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.

That's a good possibility. I however don't mind spending the time, money and effort to fix it right. I bought the car for 500$, I have about another 500$ into it as of now, so I'm not going to cry if I have to spend another 500$ to get it running well. I HOPE it doesn't cost me that much, but given what little I've put into it so far I can't really complain. Most people wouldn't be able to find any decent car for less than what I have into mine, let alone a Cadillac that's in overall very good condition. I still consider myself lucky, even if my car does have issues. That just makes it a little more like me.

[KHE]

I know you just cleaned it but it could be corroded again. On the 4.9 engines, there was a way to test the ISC switch from the climate control panel. Someone with a '94 manual should be able to post the diagnostic information. This sounds like a textbook case of a bad closed throttle switch in the ISC motor.

A few years ago, my wife said the '96 Seville was idling excessively fast and when I went to pull the hood release to begin inspecting, I noticed the floor mat was over the bottom portion of the accelerator pedal. I placed the floor mat in the correct place and the problem was gone.

[CarlaValentine]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

[Texas Jim]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

Carla,

Would it be worth risking using one from the local wrecking yard... assuming they have one.

Just wondering....

I hope you can fix the one you have.

Good luck.

[adallak]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

rockauto.com has two of them for $50 and $110

[CarlaValentine]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

Carla,

Would it be worth risking using one from the local wrecking yard... assuming they have one.

Just wondering....

I hope you can fix the one you have.

Good luck.

I considered that. There is a you-pull-it yard a few miles from me. Maybe tomorrow I will take a trip up there and see if they have anything.

[CarlaValentine]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

rockauto.com has two of them for $50 and $110

Thanks. As often as I look at prices on there I don't know why I didn't think to check myself. Any idea how long their shipping takes?

[adallak]

I did some more digging today, and finally found the problem. It IS the ISC motor. I pulled the throttle cable by hand while watching the plunger on the ISC motor, and it goes out just fine but it sticks when it should be retracting, which is causing the throttle to remain open when it shouldn't be. Next step is going to be taking it apart again to see if I can get it to stop sticking. If I can't then I guess I suck up the almost 200$ for a new one.

rockauto.com has two of them for $50 and $110

Thanks. As often as I look at prices on there I don't know why I didn't think to check myself. Any idea how long their shipping takes?

Their customer support is great and they ship fast as well. In ten years I went through three ISC motors on my 4.9 engine.

[CarlaValentine]

I just looked up the ISC motor for my car on rockauto, and it was listed at $111.89. Using my father's discount at Advance, I can get it there for under 50$, but it looks in the picture like it doesn't have the plunger attached to it, which is the part of it that I am having a problem with. Maybe I'm seeing it wrong in the picture. I'll have to go actually look at it to see if that's the case. If so, then I will order one from Rockauto.

Tomorrow I will be taking it out and trying to clean and adjust it again to see if I can get out of buying a new one. I'll let everyone know how that goes. I will also be getting all 4 of my brake rotors brought in to be spun/resurfaced so I can finally be rid of my pulsating brake issue. I hope to get the strut-rod bushings and ball joints replaced tomorrow as well, and new rear tires. It's going to be a busy day...

[KHE]

When you have the brake rotors turned, make sure to have the machine shop use a DA sander to apply a non-directional finish to the rotors as the final step.

[CarlaValentine]

When you have the brake rotors turned, make sure to have the machine shop use a DA sander to apply a non-directional finish to the rotors as the final step.

Will do. My brother is the one who is doing them, he just has to take them to where he works and use their machine since he doesn't have one of his own.

What exactly is the difference between doing it the way you suggest, and just plain ol having them turned? I've never had any rotors turned on this or any other car I've owned...I've always just bought new ones, but at about 60$ a piece for good ones, I'm going with turning them this time around. Besides that, the rotors on it are fairly new. They were put on the beginning of last summer, but then the car sat undriven for about 4 months before I bought it. Looking at the rotors, you can actually see an outline on them where the pads were resting while it was sitting.

I'll be heading out today around 2 or so to get everything done. I'll let you all know how things turn out.

[KHE]

The DA sander is the final step of the turning process that provided a non-directional finish and improved braking. Basically, the lathe operator holds a DA sander against the rotor for a certain period of time while the rotor is spinning in the lathe. This is done on both sides of the rotor.

Before you put the pads back on, sand them flat to remove any irregular surfaces on the pad. Don't breathe any of the dust from the pads.

[CarlaValentine]

So here's how my day went yesterday.

We got the front brake rotors spun, but not the rear ones because the front ones took so long to do that the place my brother works at was closing by the time he finished them. They were REALLY bad, but thankfully because they were fairly new there was plenty of "meat" left on them to cut. He had to take about 1/16 of an inch off both sides of both front rotors. 1/16 doesn't seem like much until you see it coming off your rotors. Yes KHE, he did use the sander on them afterward. When I mentioned it to him he said he was already aware it had to be done as a finishing step. I need to replace my front pads ASAP. They are very badly worn and one even has a small chunk missing from one corner of it. Eddie (my brother) said he was surprised I didn't lose a pad entirely or screw up the calipers with the rotors being as bad as they were. I plan on replacing the pads this week, and getting the rear rotors spun this weekend. Just having the front ones done has made a WORLD of difference in how the brakes feel.

As for the ISC motor....I am going to have to replace it. Cleaning and re-greasing it had very little effect on it. It's still sticking, though not as badly. I plan to buy a new one this week. I got a P036 code after tinkering with the ISC motor and test driving it a few miles. P036 = EGR pintle position out of range. Looks like cleaning the EGR system is on the roster for this coming weekend as well.

I didn't get around to the strut rod bushings or ball joints. Hopefully I can get that done in the coming week or weekend too.