So after I replaced the parts listed above with no success, I splurged and bought the Haynes manual. It gave the the accurate code description for the '54' I was getting from my dash display...no ECM communication from cam shaft position sensor. The cam shaft position sensor sits directly below the distributor (looks like a flat plastic pancake with a magnetic senor on it and a cable the plugs into connection that leads to the ECM). It cost me $60CAD to replace and about 5 minutes of my time. However, there was a bit of testing to confirm that it was bad. First you have to confirm that there is 5V DC going to the sensor which you can test by unplugging the sensor and using any fluke or digital volt meter. Then if you can confirm the voltage there, plug the sensor back in and then you have to piggy back into the back of the connection using a small but solid wire and test for a 5 V swing using an analog meter. It describes the whole process quite well in the Haynes manual ($26CAD). After I saw a continuous 5 V (no swing from 0V to 5V on a repetitive cycle), I concluded that in fact the sensor was no good and that there was nothing wrong with my ECM. In total, I spent a mere $210CAD (giving my jeep a nice tune up) and now she has been running like a dream! Don't get too freaked out when trouble shooting these babies as the easiest fix may be the right one! I really recommend picking up the Haynes manual and do the troubleshooting yourself. I am no mechanic by any means but as long as you can walk through things methodically, you should be able to at least isolate/identify the problem. I hope this may help someone someday.
Hello everyone, newbie here on CNET but found lots of great info. Here is my issue...
Engine light came on a couple of times but no change in jeep operation. Then one day the light came on as I pulled up to my home, I thought nothing of it, turned the jeep off and 2 days later when I tried to fire it up (-15C outside) it would only crank over...not fire. After doing some basic research, I realized that my jeep may have some electrical issues. I have not had the stalling problems that so many have had nor have I had the power window grounding electrical issue or weak firing or running symptoms leading up to this. The code I get on the dash odometer is 12-54-55 and from what I gather means: battery disconnect within last 50 starts-crank position sensor failure-end of codes. I have replaced my coil, distributor cap, distributor rotor, spark cables, crank pos. sensor and played around with that 2-screw on the ECM trick that so many have had success with. I see power just before the coil (12V prior to start and 9.2V when I turn it over) but I see no voltage after my coil. My first question is do I have to clear my codes after I replace my crank pos. sensor in order for this to fire? My second question is what else could it be?
97 Jeep Grand Cherokee Laredo 4.0L Straight 6.