I called a local salvage yard and asked if they had the wiring harness for the ignition module. The woman on the phone passes me to someone else and I repeat the question; yes, they have one and the price $15.00 or $20.00. Goes up five dollars right at the start. I told them I would be over to get the part. I got there and the guys goes in the back somewhere to look. So it is waiting time. Comes back and tells me that don't have one off but a LeSabre is nearby and it will only be a minute. Then the guy gets sidetrack again and I wait again. Finally he comes back and I tell him that if he is busy that I could come back tomorrow to give him time to get it off. At that point I find out he was only going to take the connector to the ICM off, cut the wires. I explain to him that I need the whole harness since mine had shorted out. Then he starts telling me that I did not tell him that on the phone, that it is a whole new game now. I ask how much and he tells me it depends on how long it will take to get it off. I don't like surprises in price. I tell him that I can take it off but will need to come back as I don't have my tools with me; not to mention to him that I was also wearing my nice clothes and not car working clothes. So he agrees and tells me that if I take it off I can have it at the original price he quoted.

Today I headed back down to the salvage yard and went to work removing the harness; shouldn't be hard since I knew exactly what to do since I had done it with mine. Not so simple. The wiring harness where it connects to the harness that goes to the firewall has a big connector and even with taking the heater hose tube out of the intake, there is no room for it to go through. I am thinking that I am going to have to remove the power steering pump. After working for way too long I noticed there is a gap behind the steering pump, but barely. I decided if I took the wires out of the loom, that each wire would pass by the gap; which they did. So that problem was finally solved. The other difficulty was the crank sensor wire. No matter how I try to turn the crank sensor connector, it would not fit up behind the motor mount. Now I got mine to come up out without a lot of difficulty. However, I had the wheel off and the wheel well cover out of the way. Finally after struggling way too long and the sun starting to get a bit too hot I decided the heck with it, I will just cut the wires near the top and repair them; which I did. I hated doing it but it appeared that I really had no choice. I couldn't take the motor mount loose. That was a really stupid way to run the crank sensor and clearly at the factory the wiring is installed on the engine and then the motor mount attached. Once interviewing for a job at Ford (which I really did not want to move to Michigan since it is too cold there) which I did not get, I told the guy that the engineers should give more thought to when someone needs to repair the cars. Probably criticising the company helped them to not hire me .

I had the foresight to bring some hand cleaner with me because my hands were filthy after getting the harness off. I clean up a bit, pack my tools away and took the wiring harness inside to pay. Not surprisingly, when I go to pay the price is now $25.00. I said OK and paid of course. Really, $25.00 is not that bad of a price to pay. I found the pigtail connector for the crank sensor at a local parts shop and they wanted close to $60 just for that one connector.

At this point I have no real hope that this will fix the problem. However, the guy that use to work at the GM dealership said that sometimes the terminals in the connectors will get loose. He stated they would have a gauge to test the fit of the connectors when they would get problems that might be related to the connectors.

jy'* that are decent are few and far between it seems

Got the harness on today. No change. Still Code 18

Oh no, I had hoped you had found the issue. I have done some searches looking for a wiring harness for you. I know you have too. I really have not found anything, and what I do find seems expensive. I know this is not new or good news for you. I am sorry I do not have any good news or any information for you. I am at a loss regarding your problem. Keep us informed and hang in there.

Doug

Kim, just so you know, I have been following this the whole time and feel the same as Doug. Like he said, hang in there.

I started to pulled the crank sensor off again. However, I just don't think that is going to be a solution. The first Duralast sensor I put on the car was working and the car ran great until the code 18. I changed the sensor again when I put the timing chain on. I did not think it was a harness problem but went ahead and replaced it anyway. What every this problem is, it is not heat related as the code sets within a minute of starting the engine. The GM shop manual first say it is a cam sensor issue but then say it is possible a fault in the 18X portion of the crank sensor. It is possible a fault with the ICM since the cam signal the PCM sees is not from the cam sensor but from the ICM as well as the fuel reference signal. However, I put the old ICM back on (replaced because I was told me it was the ICM stalling out my car) and it still threw the code 18. So would mean that both the original and the replacement ICM are faulty in the same way; not likely.

I contacted AutoZone about their Duralast sensors today, informing them that I understand electrical engineering and they could use technical jargon such as pulse width, duty cycle, frequency and so forth. Duralast are made in the USA; the original crank sensor from 93 (actually 92) was made in Mexico. There is nothing wrong with the harmonic balancer vanes; so the sensor should not miss pulses, it will either put out the square wave signal, or not. The only thing could be that if the frequency exceeds what the sensor can produce; which is determine how fast the hall effect switch can turn on and off, and I would expect the switch can switch at the speeds of an idling engine or an engine at max rpms.

I sent an email to GM because I lost the voice mail even though I saved it and the phone voice said, "message saved"; or I just don't know how to retrieve it. I did not return the call at the time because I was in the process of finding a harness and switching it out.

I was so stressed out today worrying over this that I got a huge headache. I said the heck with it and went outside and started working in the gardens, pulling weeks out of the flower beds and moving a few things. My headache and stress went away. However, I do have to fix this problem. I don't have any money to buy another car, not even a junker. Speaking of junker, it really burns me that thousands of cars were destroyed under the "cash for clunkers" that were working perfectly fine and could have been given to the poor. However, that is a different rant that I will leave be.

i really hoped that was the issue. did you closely inspect the connectors and wires to the pcm. i think you said the pcm was changed as well?

Yes, I did inspect them. I even back probed the connection at the PCM to check for the cam signal and the fuel reference signal. However, that does not necessarily mean the signal is getting through inside the PCM since I can not probe at that point. I would have to locate that point inside and solder a test point to take readings.

I have eliminated the ICM wiring harness, I have switched out the cam and crank sensors; although using the same brand. I did put the original cam sensor back on; it must not have been shorted because the car started or it could be that the guy that told me that did not know what he was talking about. I eliminated the PCM. I have switched the ICM for the original one (swapped out because heat issues may have caused the original stall problem). Note that the car ran great for four or five weeks after replacing the MAF sensor; so the problem occurred after some time of the original repair.

At first the GM shop manual states: "DTC 18 will set indicating an intermittent problem with the cam signal or the fuel control signal" So, bad wires, bad cam sensor, or an internal problem with the ICM. The cam signal and fuel control signal are generated by the ICM and sent to the PCM. Then it mentions that the 18X portion of the crank sensor or bent or missing vanes on the harmonic balancer interruptor rings.

*Same problem with two different wiring harness. (not likely both are bad in the same way and the original was repaired)
*Same problem with two different ICM; possible both were affected by the bad wiring harness in some way
*Same problem with two different cam sensors; possible both were affected by the bad wiring harness in some way.
*Same problem with two different crank sensors; possible both were affected by the bad wiring harness in some way.

Here is a point about the cam sensor, I could test for the cam signal at the back of the PCM connector, and it went from +5 to 0 volts just as it should. So that tells me that the cam sensor was working as it should. That was by rotating the crank by hand. I have not checked with the engine running; running the voltage is less than 5 is all the manual says. As I said before, I really need an oscilloscope to see what is happening with the engine running.

I am wondering if it is something else beside what the GM shop manual is telling me. The manual does not indicate the ICM can be at fault at all. The shop manual I have, I am guessing, is from back in '93. What I was hoping that GM could tell me if after the shop manual was printed that updates or service bulletins on the problem was published.

Here is an update. I decided to pull the harmonic balancer pulley and put the original crankshaft sensor back on. Still code 18. Put the original cam sensor back on. Still code 18. It seems I have eliminated just about everything that could cause this code 18, cam/crank error. I am going to reinspect the connectors where they plug into the PCM/ECM. If one recalls, I eliminated the PCM/ECM as a possible cause.

I am still wondering if something besides what is stated in the book is causing this problem.

Any update or solution to your issue?