WJ Cruise Control In-depth Troubleshooting - JeepForum.com

 
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post #1 of 4 Old 03-14-2014, 01:19 AM Thread Starter
tinklybear
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2001 TJ Wrangler 
 
Join Date: May 2009
Location: Sacramento
Posts: 51
Wj WJ Cruise Control In-depth Troubleshooting

This is on my Father's 2001 WJ Laredo with a 4.0L. Current status: Light turns on and stays on until you press set, the light goes off soon after that and will not on again until you shut off and start the jeep.

I have gone more in-depth than any of the threads I have found, but still have not nailed down the problem. My current questions I am trying to answer are in bold below.


Steering wheel switches: Unplugged the C3 connector from the PCM, and used a multimeter to measure the switch resistances between Pin 32 of the connector and ground. Cannot find what proper numbers are for this (not listed in FSM for WJs), but I think it's good all the numbers are different and non-0
Results:
  • On/Off 459 Ohms
  • Set: 4300 Ohms
  • Res/Accel 15,400 Ohms
  • Cancel: 1,220 Ohms
  • Coast 2,920 Ohms

Brake pedal Switch: At C3 connector pins 11 and 24, I verified resistance when brake pedal is pressed (I think 20kOhm) and ~0 when pedal is not pressed.

Vacuum Lines: Vacuum lines appear to be in good condition. After not running the car for a few hours, there was still vacuum in the hoses when I removed the CC servo for testing

CC Servo: Removed unit and pushed on the vacuum diaphragm(where the cable connects), moves smoothly, I am not sure how hard it to should be to compress but it seemed sort of reasonable and it rebounds on its own. Vacuum soleoid (center) moves with 5V. Other two solenoids (vent and dump) will not move with 5V but will move with 6V. Not sure what voltage they are supposed to move at, it is not listed anywhere. Reinstalled solenoid servo and tested it by applying a 9V DC signal to connector C3 Pin 11 and grounding to the frame and could hear multiple solenoids clicking in the CC unit. Tried applying a vacuum with a manual pump, then actuating the solenoids. There was a little tension of the cable, but it quickly lost the vacuum I built with the pump so it relaxed. Does this mean that my solenoid unit is leaking and needs replaced?

Cable: Cable is connected but seems to have a significant amount of slack in it. Tested by placing a camera and flash light under the hood while driving. There appeared to be tension in the cable for a brief moment when pressing the set button, but it quickly slackened, I will try to post the video tomorrow. Cable may be too long? I will measure the amount that sticks past the throttle connecter in the morning, can someone with a working CC help me out by measuring theirs for comparison?

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post #2 of 4 Old 03-14-2014, 05:14 AM
shockracer
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Join Date: Oct 2010
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Posts: 1,639
Quote:
Originally Posted by tinklybear View Post
This is on my Father's 2001 WJ Laredo with a 4.0L. Current status: Light turns on and stays on until you press set, the light goes off soon after that and will not on again until you shut off and start the jeep.

I have gone more in-depth than any of the threads I have found, but still have not nailed down the problem. My current questions I am trying to answer are in bold below.

Steering wheel switches: Unplugged the C3 connector from the PCM, and used a multimeter to measure the switch resistances between Pin 32 of the connector and ground. Cannot find what proper numbers are for this (not listed in FSM for WJs), but I think it's good all the numbers are different and non-0
Results:
[*]On/Off 459 Ohms[*]Set: 4300 Ohms[*]Res/Accel 15,400 Ohms[*]Cancel: 1,220 Ohms[*]Coast 2,920 Ohms


Brake pedal Switch: At C3 connector pins 11 and 24, I verified resistance when brake pedal is pressed (I think 20kOhm) and ~0 when pedal is not pressed.

Vacuum Lines: Vacuum lines appear to be in good condition. After not running the car for a few hours, there was still vacuum in the hoses when I removed the CC servo for testing

CC Servo: Removed unit and pushed on the vacuum diaphragm(where the cable connects), moves smoothly, I am not sure how hard it to should be to compress but it seemed sort of reasonable and it rebounds on its own. Vacuum soleoid (center) moves with 5V. Other two solenoids (vent and dump) will not move with 5V but will move with 6V. Not sure what voltage they are supposed to move at, it is not listed anywhere. Reinstalled solenoid servo and tested it by applying a 9V DC signal to connector C3 Pin 11 and grounding to the frame and could hear multiple solenoids clicking in the CC unit. Tried applying a vacuum with a manual pump, then actuating the solenoids. There was a little tension of the cable, but it quickly lost the vacuum I built with the pump so it relaxed. Does this mean that my solenoid unit is leaking and needs replaced?

Cable: Cable is connected but seems to have a significant amount of slack in it. Tested by placing a camera and flash light under the hood while driving. There appeared to be tension in the cable for a brief moment when pressing the set button, but it quickly slackened, I will try to post the video tomorrow. Cable may be too long? I will measure the amount that sticks past the throttle connecter in the morning, can someone with a working CC help me out by measuring theirs for comparison?
Check all your vacuum lines. Mine was doing the exact same thing until I found a split in the line on the passenger side under the battery.

I know I still have another bad line some where as it will cancel its self out if I'm setting it at 60MPH or faster.

2001 WJ 60th anniversary edition 4.7 quadra-drive
5" hybrid lift, 265/70/17 Guard Dogs load E, bilsteins 5100's, addco sway bars, JKS front quick disco's, JKS adjustable track bar, KOR durometer track bar bushings, IRO crucial path front L.A.s, 1.25" Spidertrax spacers

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post #3 of 4 Old 03-14-2014, 09:19 AM
swkenobi
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2003 WJ 
 
Join Date: Jun 2009
Location: Colorado
Posts: 151
+1 on above. It's so cheap to just go get some vacuum hose and replace all of it especially the part that runs under the battery tray and behind the headlight. I think I spent $6 on it.

2003 Grand Cherokee Limited - Mostly Stock
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post #4 of 4 Old 03-17-2014, 07:50 PM Thread Starter
tinklybear
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2001 TJ Wrangler 
 
Join Date: May 2009
Location: Sacramento
Posts: 51
OK I will physically check all of the lines, but they did seem to hold vacuum well when applied with a vacuum pump
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