briandors Posted September 7, 2005 Report Share Posted September 7, 2005 I just went through this ordeal, so I thought I'd share some tips. I won't cover what the CPS does, or how to diagnose it. Once you've determined you need to change it, here are some strong "hints". 1. It's located on the back of the block. On an 89 3.1 I was able to crawl under and work on it from the bottom. Find a two-wire connector. Connector is set at a 90 degree angle to the block. 2. After Unplugging connector and moving it well out of the way, you need to soak where the sensor meets the block (all the way around) with some type of cleaner or penetrant. The advise I got was CARB cleaner, because there is coking from the engine that needs to be broken down. I used Berryman's and it helped. NOTE that carb cleaners can be VERY toxic!! Where it touched my hands, my hands were burning. Wear gloves, eye, nose/mouth protection. Actually I didn't even spray the stuff directly. I took a cotton ball, soaked it in the cleaner, and then patted around the area. If you have the luxury of time, I recommend you soak, wait a day, soak again. 3. When you go to pull the sensor, be gentle. The plastic will be very brittle from the years. Try to pull straight out when you are pulling. Occasionally twisting it (but never side to side) will help. You may have to resort to using a screwdriver to pry. If so, try to use a very wide screwdriver, and better yet put one on each side of the sensor and work them together. If you hear cracking, in my opinion, stop and soak it some more. 4. If it breaks (and it did for me), and you don't have anything you can grab with pliers or it broke too deep to insert pliers, the advice given me was to take a metal pick or a drywall screw and heat it up red-hot with a torch, then poke into the plastic sensor. Allow to harden and cool, then pull out. NEVER do this with carb cleaner or other solvents in the area, wait till those have completely dried. I chose a drywall screw about 2.5" in length, locked into vice grip pliers. I had a helper heat the screw red hot (stuck my arm out from under the car), and then i gently but with some pressure pressed into the sensor. Wait two minutes, and pull. Repeat over and over and it comes out. Yes there are other possibilities (pushing it out from the inside if you've dropped the oil pan, or pushing it into the block and then leaving it or taking off the pan to get it out) but I believe this is the fastest way. Hope this helps someone! Brian Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 7, 2005 Report Share Posted September 7, 2005 Good info! Moving to the correct section. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted September 7, 2005 Report Share Posted September 7, 2005 This should really be in the FAQ section. Excellent. Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 7, 2005 Report Share Posted September 7, 2005 go for it Quote Link to comment Share on other sites More sharing options...
Pabz Posted September 7, 2005 Report Share Posted September 7, 2005 Why did you have to replace this, what problems were you having? Quote Link to comment Share on other sites More sharing options...
briandors Posted September 8, 2005 Author Report Share Posted September 8, 2005 Car stalled while driving. I tested for spark, no spark. Tested resistance across coils, they were good. At that point I could have tested the ignition module or gone after the CPS. Without a scope ( I only own a voltmeter),,, I took a chance and went after the CPS since its much cheaper than an ignition module. Quote Link to comment Share on other sites More sharing options...
joey b Posted September 8, 2005 Report Share Posted September 8, 2005 Use caution when removing the sensor. Mine was broken and could not be pulled out. The broken part was hanging at an angle inside of the block. I had the engine out already and it did not matter that the broken piece fell into the oil pan. There was no reason for it to have broken, it just broke one day and less that a week later spark knocked so bad that it broke my piston in half. Quote Link to comment Share on other sites More sharing options...
pwmin Posted November 5, 2005 Report Share Posted November 5, 2005 thx. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted December 9, 2005 Report Share Posted December 9, 2005 also for automatic LQ1 guys, you have to pull the alternator to get at it. and in my case it was also VERY stuck in there and the top of it broke on removal, to remove mine i ended up drilling a hole in the center of it with a dremel tool and screwing in a drywall screw, and out it came. and for automatic 2.8/3.1 guys i've found you can get at it from the top as well, its not too bad if you got small hands and skinny arms and reach down next to the engine on the passenger side and under. Quote Link to comment Share on other sites More sharing options...
bigdman Posted January 20, 2006 Report Share Posted January 20, 2006 same happend to me, i was at my girlfriends house one night i went outside to go home and my car wouldn't start i was pulling out the sensor and it broke off inside the block (never thought of using carb spray anr anything else) i threaded a drywall screw in the sensor and worked it loose, the it popped right out Quote Link to comment Share on other sites More sharing options...
loominaz34 Posted January 20, 2006 Report Share Posted January 20, 2006 I would also add tthat some antiseize on the side of the sensor would make this job a million times easier the next time it has to be done. Mine was antiseized and it came right out. Quote Link to comment Share on other sites More sharing options...
creepin_olds Posted March 11, 2006 Report Share Posted March 11, 2006 Just a quick question. I have a 90 GP with 3.1 MPFI. Started jerking on me really bad coming down the road and then just turned off. After letting it sit for a little while it would start back up for about 2-3 minutes and then turn back off. Mky mechanic was able to determine there was no spark~ So does this sound like the crank sensor to you guys or does it sound like the control module? also, if it is the CPS, why would it only turn off whenever it got hot just out of curiousity? any ideas? or do u think it might be more than that? I just need some ideas guys and normally how long does it take to get an oil pan off. Just out of curiousity. I took one off but it was already out of the car. How long does it take if it is still on the car. ? and also how much do u guys think I should be looking to spend to get her fixed right again? Kris Quote Link to comment Share on other sites More sharing options...
joberlee Posted March 25, 2006 Report Share Posted March 25, 2006 That sounds like a bad ICM to me. They have a tendancy to wok when they are cold and shut off when they get hot, before they stop working completely that is Quote Link to comment Share on other sites More sharing options...
Crazy K Posted March 25, 2006 Report Share Posted March 25, 2006 That sounds like a bad ICM to me. They have a tendancy to wok when they are cold and shut off when they get hot, before they stop working completely that is That would most likely correct. Ask my 92 lumina which lost it's Ignition control module on the middle of a crowded highway in the middle of nowhere Virginia! It would restart and then stall after I rejoined traffic again and again.... over and over..... But, I also discovered the crank sensor was full or cracks, which will allow soot and oil from the engine to penetrate it's internals and make it fail. Symptom observed during a stall: TACH FAILURE. The signal to feed the tach, and the ecm as well would stop being generated. If you try to start a car with a tach and a bad Crank Sensor or ICM, most likely the tach would not budge or might jerk/snap/hop/pop... basically a phantom 'tick'. Check your crank sensor no matter what. Quote Link to comment Share on other sites More sharing options...
CSupremeLover Posted April 9, 2006 Report Share Posted April 9, 2006 Actually diagnosing the sensor is not so hard. 1. unplug the sensor wire. 2. using a DIGITAL AC VOLT METER tester that will read Millivolts (0-500 mV) place leads on each prong of THE ACTUAL SENSOR 3. hold and have someone crank engine. 4. should see SOME type of reading. If using a very basic LED light it should Blink on and off. That is normal. Any reading or blinking light means it is good. If you get no reading make sure that you are connected properly, that the meter reader reads M i l l i V o l t s and is AC. If LED light stays ON steady.....Sensor BAD If LED light blinks ON/OFF.......Sensor GOOD If you get any reading on meter (even if it fluctuates) Sensor is GOOD. Plug back in and check something else! Hope that helps someone Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted July 17, 2006 Report Share Posted July 17, 2006 For the shortstar 3.5 DOHC v-6 in Intrigues and Auroras the CKP is located under the starter its secured by a 10mm bolt holding it into the side of the block very easy to get to when you pull the starter off, BEFORE doing this remove your negative battery cable. Quote Link to comment Share on other sites More sharing options...
Slade901 Posted September 12, 2006 Report Share Posted September 12, 2006 I've replaced the CKPS twice in three years. The first time the CKPS resistance reading was very low compared to a new one. This time, I got no spark condition. I disconnected the CKPS connector to the ICM, I connected my digital multimeter on the disconnected plug and I do not get any resistance reading. I want to make sure that the wires are fine, I went underneath and disconnected the connection cable from the CKPS itself. I put a jumper wire on the disconnected cable off from the CKPS end and measure for resistance on the other end of the connection cable (ICM side) and I got a reading (after the other end was jumped with a wire). So, I replaced the CKPS and it works and I got sparks now. Quote Link to comment Share on other sites More sharing options...
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