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2003 Yukon xl 1500: DTC C0660 shows up on code reader..compressor

Customer Question
DTC C0660 shows up on...
DTC C0660 shows up on code reader after being cleared at each start-up. Level Control Exhaust Valve Circuit Malfunction. 6 month old compressor on 2003 Yukon xl 1500 will not start running. Old compressor stopped running before but no code so I replaced it and was fixed. Service Auto Ride message came up so I checked my connections and they were corroded. Redid and was fix briefly, message dissappeared. Message Back! Power appears to be getting to compressor. I cleaned and redid all connections and cleaned and reattched grounding wire. Pump not running. Think pump was running more than normal so may be leak in air assist shocks that wore out pump. Thinking about buying another compressor and replacing air assist shocks for about $600 hoping that fixes it. RTD 30 amp fuse appears fine. Do not know where exhaust selonoid is. Do not know how to access suspension control module (ECM). Tired of Googling. How do I fix this issue least expensively? 170K miles on vehicle. Thanks
Submitted: 8 years ago.Category: Chevy
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Answered in 13 minutes by:
2/13/2009
Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago
Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 9,164
Experience: Working with Electronics & Cars for 25+ Years
Verified

Hello & Welcome,

 

Let me give you the troubleshooting chart for this particular code. I will be back in a few minutes to send along the schematics.

 

C0660 Chart

 

I assumed this is aXXXXX Please let me know if this is not correct.

 

I also noticed that you did not say that you measured the voltage at any fuses or test points. Do you have a voltmeter or test light that you can use?

 

Thanks, XXXXX

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Customer reply replied 8 years ago
Greg, not very experienced. I put test light on main harness connector. I want to say there are 6 connections and 3 gave me voltage. I tested all four wires going to coming to or from compressor. Blue hot, white cold, red cold, black cold. It is 4X4.
Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again,

 

Here are the schematics that go along with that chart.

 

Compressor Motor Control.

 

graphic

Suspension Level Control

 

graphic

 

Try to look at the chart and see what you can do with these schematics.

These should help you identify what voltage should be at different points in the system.

 

Please let me know if you need more information or help.

 

Thanks, XXXXX

 

 

 

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Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again,

 

I just got a note from another expert here that I wanted to pass along.

 

The problem is with water getting into the exhaust solenoids. That causes the system to go inop when it sets that code. If you get a realy with about 30 ohms of resistance and jumper that into the connector-it will not set that code but other codes if the connector is unpluged. That fresh air vent needs to be relocated from the gas filler pipe area.

 

I hope this helps.

 

Take Care, Greg A.

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Customer reply replied 8 years ago

I was afraid you were going to send me something like this...I mean that politely by the way. This may be way over my head. I guess this means if I find incorrect voltage after a point, replace that point. I believe the problem started with our winter thaw and large puddles.

Where exactly is the exhaust solenoid?

What does jumper that relay into connector mean? What connector?

I think you may be onto something with this.

I still do not understand how to fix this. What does fresh air vent look like? Black tube?

Do I dettach the air vent to drain or dry or is solenoid probably shot?

Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again,

 

Don't worry too much if you feel you may be in to deep. I just want you to understand the system so that IF you have to take it in to be repaired, you can ask the right questions so that you don't get charged for replacing the entire system, when only one piece is required.

 

If it started with large puddles, the would tend to confirm that the problem is water getting into the exhaust solenoids. These are located on the compressor to let air out of the system so that the level of the vehicle will go down.

 

These is also an air 'input' on the compressor, and a little bit of electronics in the area. So if water gets into the system, it can mess up the exhaust, or the electronics (solenoid). What the other expert was saying is that air vent really needs to be moved, so that there is less of a chance of getting water into the system.

 

I believe the relay he was referring to is the control relay, which is shown in the first schematic. Below are the two diagrams that show the location of the ALC (Auto-Level Control) system.

 

graphic

 

graphic

 

Let me see if I can find the system description for you, so you will have the "Big Picture" of how the system works, or is supposed to work.

 

Thanks, XXXXX

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Chevy Mechanic: frank, Chevrolet Technician replied 8 years ago
frank
frank, Chevrolet Technician
Category: Chevy
Satisfied Customers: 3,420
Experience: 33 years experience,24 years of Chevroler/GM experience and training .ASE Recertified Master Tech,
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Gregg Sorry to over post but the site has problems and wanted to pass this on to peatman-If you look at the compessor-there is a connector hidden by that rubber sheild-look at the schematic The exhaust solenod can be checked with a ohm meter there.Look at the color wires-the spec is more then 15 ohms ,but less then 20 ohms will set that code.The vent is on the inside if the fender behind tied into the gas fiiler pipe-its a vacuum hose with a black box for a vent on it.And I have found out-even with the new style vent-with it located by the gas pipe it sucks water into it in wet areas and shorts that solenoid-I relocate the vent to over the spare so the sare sheilds it.The solenoid is not sold seperatly since its buildt into the compress

ore-years ago it was when we rebuildt them.

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Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Thanks Frank.

 

I tried to get back to you (in a couple of ways). I'm sure peatman will not mind.

 

Take Care, Greg A.

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Customer reply replied 8 years ago
Pulled both ends of vent exhaust tubbing off, no water! Reset code and hear what sounds like the solenoid tripping immediately after the reset in driver rear and message and code remain or re-code on each reset. Will try anther new compressor from Arnott while I am checking ohm readings. Let me know when you have run out of suggestions and I will acccept, thanks.
Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again,

 

I was going over this message thread again, and the diagnostic chart, and it looks like it would be kind of hard to do a few of the steps without the use of a scan tool that is capable of giving commands to the system to turn things on & off (steps 2, 5, & 6). But you should be able to check the resistance of the exhaust solenoid by removing the connector and probing pins B & F (from the schematic). As the chart says, 18-45 ohms should be OK, but right in the middle of that range is best.

 

Since this code is set when the ESC (Electronic Suspension Control) Module detects some kind of issue when trying to control the exhaust relay, I would also check what is happening between the controller connector - C2 to be specific - at Pin B5 (shown on the schematic). This module is in the right rear of the vehicle, as shown below. I also noticed that this wire (between the ESC & the exhaust solenoid) also goes through a pass-through (P475) and another in-line connector (C450). Any rubbing as the wiring goes through the body, or a loose in-line connector could have an effect.

 

graphic

 

graphic

 

You should also be able to apply power and ground directly to the compressor motor (pins A & G respectively) to make the compressor motor run, as a test. You could also do the same for the exhaust solenoid, but all you would notice is a clicking of the solenoid, and possibly some escaping air. But at least you could test these pieces and see if they appear to function.

 

Please let me know what you find.

 

Take Care, Greg A.

Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 9,164
Experience: Working with Electronics & Cars for 25+ Years
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Customer reply replied 8 years ago
We'll try all that, thanks and will report back.
Customer reply replied 8 years ago
Greg, no schematic showing pins A & G to apply power. Same for exhaust solenoid test with power. How do I apply power, spare battery and wires. Thanks.
Customer reply replied 8 years ago
No schematic showing pins B&F? I have compressor off vehicle. I disconnected the large wire connector connected to the pigtail going to the compressor. I tested each pin in that connector. With key on one pin shows 29.4 ohm. I do not appear to have the schematics refering to pins B&F and A&G. I assume it would show picture of connector with each pin labeled?
Customer reply replied 8 years ago
OK here is what I found, with ignition on I have almost 12 volts feeding one pin in main connector. Middle row of three pins, left side. It appears to be going to dk blue wire to exhaust solenoid. This pin location has 20.4 ohm resistance. No voltage on other side of exhaust solenoid. No resistance on other side of exhaust solenoid. I think the exhaust solenoid is bad! I cannot get exhaust solenoid or compressor to do anything with power being fed to both. So if solenoid is bad I assume nothing will happen with entire unit since that appears to initiate all functions. I will replace compressor unit with exhaust solenoid and see what happens.
Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again & thanks for the accept.

 

Sorry for the delay - I am in the pacific time zone.

If the compressor is off the vehicle, you could use a spare battery and wires to apply power & ground directly to the appropriate pins to get the compressor motor to run or the solenoid to activate.

 

I finally found the pin diagram for the compressor connector. Circuit numbers and wire colors are included, and should match the schematics.

 

graphic

 

Please let me know how it works out.

 

Take Care, Greg A.

 

 

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Customer reply replied 8 years ago
Thanks, XXXXX XXXXX unit off. grounded unit and hooked car battery to it with jumper cable to solenoid and then to the compressor. Neither would spark, wiggle, make noise, nothing.
Chevy Mechanic: Greg A, Master Troubleshooter replied 8 years ago

Hi again,

 

I have drawn on the connector diagram (below) on what you would have to do to get the compressor motor and the solenoid to activate with jumper wires & a battery. Just grounding may not be enough to make them work.

 

For the Compressor Motor:
Apply +12 volts to Pin A (Light Blue wire) and Ground to Pin G (Black wire)

 

For the Solenoid:
Apply +12 volts to Pin F (Orange wire) and Ground to Pin B (Dark Blue wire)

 

You should see the wire colors coming out of the pins I have mentioned above in parenthesis.

 

If the motor or solenoid do not activate, then they are bad.

 

graphic

 

Take Care, Greg A.

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