Where is the PCM located?

Tiny
DANERESCUEMOM
  • MEMBER
  • 1993 SATURN SL1
  • 75,000 MILES
I am trying to remove a PCM module on my grandson's vehicle listed above and need to know where it is under the dash. It is idling very high, and this is the only thing I can come up with. It has been on the scanner and hours spent so if you can tell me where it is because I know I will break the clips when I remove them, not sure if it is on the left or right. Thank you- a very tired grandmom.
Wednesday, June 26th, 2024 AT 1:51 PM

21 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
High idle but no other issues is commonly a vacuum leak or IAC problem not a PCM failure. I would start there myself as the PCM would normally be showing a code 35 and not just a high idle. Don't forget to check the power brake vacuum line as well as a bad vacuum booster could also cause a leak. The attached shows the vacuum lines in question. The easy way to tell if it's a vacuum leak is to start with a cold engine and a can of carb cleaner. Start the engine and spray the cleaner along the lines and around the intake manifold gasket area. For the brake booster, disconnect the line and plug it.
If you are sure it's a bad pcm then it is under the left side of the dash in a carrier between the steering column and the kick panel.
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Wednesday, June 26th, 2024 AT 7:39 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
We tried 4 IAC aftermarket valves and none of them moved. They all stayed in the same position. ;(
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Thursday, June 27th, 2024 AT 5:06 AM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you for the diagrams and all this info. I will be doing this tonight when I am done trying to fix my washing machine now as well. Any info you have I would be so appreciative as I am at a loss of what else to do but this is very helpful and will do tonight on a cold engine. Thank you. You are a blessing as my 22-year-old grandson needs this car. Thank you.
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Thursday, June 27th, 2024 AT 5:17 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
If the IAC didn't adjust I would start with the leak testing. They may have closed down because the idle was already too fast and they couldn't make it lower. If you don't find any leaks then we will do some testing on the electronics to see if there is a wiring issue, but vacuum leaks are common as the rubber parts age and decompose. Washing machines are fun to work on.
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Thursday, June 27th, 2024 AT 11:11 AM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you. You are awesome. I will do this all tonight with a cool car engine and I think the washer is easier than the car. Lol. Dealing with water leaks is way easier. - The bleach fill line got disconnected- so 1 down let's hope the car will be this easy. Thank you blessings.
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Thursday, June 27th, 2024 AT 11:42 AM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Here is what I found. At the hole with the yellows arrows, this is where it is sucking tremendous air! It looks like this is where the IAC valve would be. It I cover it, it idles fine. Should there be something there thats missing? Or does this hole just be there doing nothing but supplying air to the IAC. I am at a loss for why it could be sucking so much air all of a sudden. Thank you.
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Thursday, June 27th, 2024 AT 5:17 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Sorry if I cover it. It idels fine. And yes it will suck your finger off. Thank you sir.
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Thursday, June 27th, 2024 AT 5:18 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
The carb cleaner was sprayed, and no leaks were found except for this portal. We also used a smoke machine and that's the only place smoke came out. Engine was off. Smoke was ran through the brake booster hose. Thank you
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Thursday, June 27th, 2024 AT 5:21 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
Okay, that means the IAC isn't adjusting itself and is stuck wide open. The IAC in that vehicle uses 2 coils that move the stepper motor to move the pintle to block the passage. The IAC is supposed to reset to full closed when you shut off the car then it opens back up when the engine starts. They make a special service tool for it or if you have an OBD I scan tool that can adjust it you could easily test it. To test it without a scan tool you can use a test light to probe into the back of the connector with needles. Then you could watch to see if the power is there to pulse the IAC, Then you would go to the PCM and check the connections there. That would show you if it's the wiring or the PCM output. There are a few videos out there that show how to back probe the connector. That lets you test it with it installed.
The light would get connected to one pair then to the other pair. So the two light green wires, then the two blue wires. It should blink as the IAC adjusts.
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Thursday, June 27th, 2024 AT 6:05 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you so very much. This will be the next thing I do. I am printing this info so I dont get confused. And hopefully the next few days I can get to this. Thank you. I will let you know what happens with this. You are a blessing to me I cant even tell you. As soon as I get some time I will get on this testing next. Thank you. I will be in touch hopefully in the next few days. - Nancy.
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Friday, June 28th, 2024 AT 4:11 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
We will be here when you need us.
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Saturday, June 29th, 2024 AT 8:54 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you. Okay, did the wire test yesterday. There is power to the aftermarket ICA motor it moves but is still sucking air. (The aftermarket moves better than the original) so what can I test or do next? Thank you.
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Sunday, June 30th, 2024 AT 4:15 AM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Where the air is being sucked in is there supposed to be a covering or a flap or something in there to control it? As when it is covered it idles fine. Do you think that unit - throttle body assembly- could be the issue? And not just the IAC and how hard would it be to find that entire part. And how do I find that part number? Thank you.
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Sunday, June 30th, 2024 AT 4:45 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
There could be a bad gasket and the rebuild kit does contain them, but that passage should go down to the IAC. The IAC should extend out and block a hole inside the throttle body. When you block that port you are acting as the IAC motor.
You have power on both sets of wires? That means it shouldn't be the PCM, it's something with the IAC or the throttle body. Perhaps pull the IAC off and check in there to be sure the seat is clear and nothing is there to hold it open.
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Sunday, June 30th, 2024 AT 3:14 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you. Yes, power to both sets of wires. We managed to get something to block the hole until we can get it figured out as he needs his car and I can't have him driving it with a 3000+ RPMs going as far as he does. It is keeping a little at 1300 for now with a ""blocker"" we had the IAC off and all cleaned up and nothing is blocking it from moving. So, I am also thinking about the throttle body. I saw Ebay has some so might go ahead and get a used one and hope that works. Praying that the little ""blocker"" holds up for now. If you can think of anything else, please let me know as this is driving this old lady nuts. And I just need him safe. Thank you for your kindness. I will let you know how it goes as soon as I can get that piece. Nancy
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Sunday, June 30th, 2024 AT 6:00 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Just went back on ebay and looked an none of them look like what we have. So gonna have to do some more research and see if I can find one. Thank you.
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Sunday, June 30th, 2024 AT 6:10 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,007 POSTS
The rebuild kit is a Standard Motor Products #1695 rebuild kit. If it's a bad gasket or internal issue that kit should repair it.
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Sunday, June 30th, 2024 AT 9:55 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you. I will see if I can find this to buy asap. Keep fingers crossed as most parts advertised aren't correct I am finding. If you have any suggestions on where to find them- I am sure they won't be OEM, please let me know. - Out to milk cows. Thank again
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Monday, July 1st, 2024 AT 3:59 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

I noticed no one has contacted you for a couple of days. Have you been able to make any progress?

As far as the PCM, it is located to the left of the steering column under the dash. The mount that holds it in place also holds the ABS module. I attached a pic below.

Let me know if that helps. Also, pic 2 provides the original part number. Note there are two. One is for an automatic transmission and the other is for a manual transmission. I'm not sure which you have.

Let me know if you have other questions.

Take care,

Joe

See pics below.
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Thursday, July 4th, 2024 AT 7:52 PM
Tiny
DANERESCUEMOM
  • MEMBER
  • 16 POSTS
Thank you. No I haven't been able to do anything. The grandson went to Nova scotia for 12 days so I am going to try to do more when he is gone. It is just hot as heck, I know no excuse, and tons of other things to do. I did reach out to a junk yard to see if they have the housing unit - throttle body and since it was a holiday yesterday won't hear back until I am guessing next week. For now, I have a piece of heavy material jammed in there and silicone and the idle is okay. Since he is away I have some time where it isn't being used. Thank you so much. You all have been amazing. I have ton of other things happening at the same time, my tractor is giving me problems and I have hay to move, so I am being stretched to my limit and it is hot. Lol- thank you as soon as I get back to it I will post. Or if I get a part, be it the rebuild kit or a new housing I will let you know. Thank you for reaching out. Blessings. Nancy
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Friday, July 5th, 2024 AT 4:09 AM

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