acfortier Posted October 10 Share Posted October 10 OK, now this is a new symptom. I've been dealing with a crank, no-start issue outlined here: https://comancheclub.com/topic/72314-another-crank-no-start-issue and tried to tackle it again today. Started it up, no problem. Left it running to walk away into the basement for a second, and came back and it was off. BUT, I could hear the fuel pump cycling on and off rapidly, which was really odd. Took out the phone for a quick video: https://drive.google.com/file/d/1RCUkOpcXoGe4e-vn1CPgN7IVAXKmLuZJ/view?usp=sharing As you can see, it's acting as if I'm cycling the key from OFF-ON-OFF-ON etc. but the key has been in the ON position the entire time. I've never noticed this before, and definitely seems electrical, but I'm not really sure where to start? Is it the ignition switch causing this? Link to comment Share on other sites More sharing options...
acfortier Posted October 10 Author Share Posted October 10 OK, checked ignition switch, no burnt wires/terminals or anything. Happened a few more times as I was troubleshooting, but didn't seem to correlate to what I was doing (moving the connector up/down, moving the wires up/down). Couple times the engine would throttle down, then shoot back up higher, then come back to a normal idle. Link to comment Share on other sites More sharing options...
89 MJ Posted October 10 Share Posted October 10 This does seem like an electrical issue, but I also wonder if it could be something with the rod going to the ignition switch. Do you have a tilt column by chance? If so, see if it does it if you change the angle of the column. The PO of my Eagle would always have a hard time getting the car to crank or shutoff, but that's because he had the column all the way up. I have the column more straight, so I don't have that issue. I wonder if you are having a similar issue where the ignition switch is getting turned on and off somehow. Otherwise, how do the battery connections look? Link to comment Share on other sites More sharing options...
acfortier Posted October 10 Author Share Posted October 10 9 minutes ago, 89 MJ said: This does seem like an electrical issue, but I also wonder if it could be something with the rod going to the ignition switch. Do you have a tilt column by chance? If so, see if it does it if you change the angle of the column. The PO of my Eagle would always have a hard time getting the car to crank or shutoff, but that's because he had the column all the way up. I have the column more straight, so I don't have that issue. I wonder if you are having a similar issue where the ignition switch is getting turned on and off somehow. Otherwise, how do the battery connections look? No tilt column. I did try jiggling the key/ignition while it was running to see if I could get it to do something, but nothing was conclusive. Battery connections are brand new. Just upgraded to the Big 7 (although, I only did the Big "4"--negative to engine, negative to fender, positive to PDC, positive to starter) Link to comment Share on other sites More sharing options...
ghetdjc320 Posted October 11 Share Posted October 11 I feel compelled to repeat myself here: have you tried a NEW battery? . Don’t assume it works because it cranks or shows voltage with a meter. You keep having issues and have tried all sorts of diagnostics. The fuel pump prime comes from the ecu and not directly from the ignition switch. Link to comment Share on other sites More sharing options...
acfortier Posted October 11 Author Share Posted October 11 10 hours ago, ghetdjc320 said: I feel compelled to repeat myself here: have you tried a NEW battery? . Don’t assume it works because it cranks or shows voltage with a meter. You keep having issues and have tried all sorts of diagnostics. The fuel pump prime comes from the ecu and not directly from the ignition switch. I almost preemptively tagged you in the post... alright, new battery coming today since I'm out of ideas. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted October 11 Share Posted October 11 24 minutes ago, acfortier said: I almost preemptively tagged you in the post... alright, new battery coming today since I'm out of ideas. Link to comment Share on other sites More sharing options...
acfortier Posted October 12 Author Share Posted October 12 Well, installed new battery, started a couple times and let it idle and didn't have any issues. Went outside this AM to do the same thing, and it died after a few minutes. Tried to start it again, crank-crank-crank-crank. Took another video because this seems really weird--I feel like the Check Engine light and others should start illuminated longer than they are when putting the key into ON? https://drive.google.com/file/d/1xWpoduznIcf90QYQUEk4af7FvGZyhk9l/view?usp=drive_link Link to comment Share on other sites More sharing options...
ghetdjc320 Posted October 12 Share Posted October 12 7 hours ago, acfortier said: Well, installed new battery, started a couple times and let it idle and didn't have any issues. Went outside this AM to do the same thing, and it died after a few minutes. Tried to start it again, crank-crank-crank-crank. Took another video because this seems really weird--I feel like the Check Engine light and others should start illuminated longer than they are when putting the key into ON? https://drive.google.com/file/d/1xWpoduznIcf90QYQUEk4af7FvGZyhk9l/view?usp=drive_link Have you replaced the CPS? Link to comment Share on other sites More sharing options...
acfortier Posted October 12 Author Share Posted October 12 58 minutes ago, ghetdjc320 said: Have you replaced the CPS? I did, but that was prior when I was having the same issue due to a poor connection at the ignition coil awhile back. Since this issue popped up again, I ended up putting the original CPS back in since I knew it wasn’t the original issue, but the current problem still persisted. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted October 13 Share Posted October 13 1 hour ago, acfortier said: I did, but that was prior when I was having the same issue due to a poor connection at the ignition coil awhile back. Since this issue popped up again, I ended up putting the original CPS back in since I knew it wasn’t the original issue, but the current problem still persisted. Interesting. If it starts fine while cold but dies when warm, CPS is definitely up there on the list. Link to comment Share on other sites More sharing options...
acfortier Posted October 13 Author Share Posted October 13 27 minutes ago, ghetdjc320 said: Interesting. If it starts fine while cold but dies when warm, CPS is definitely up there on the list. I don’t think it has enough time to get warm to be honest. It wasn’t idling for more than 5 minutes last time it happened. Can someone confirm if the Check Engine light should stay illuminated longer when they key is ON but the engine is not running? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted October 13 Share Posted October 13 Have you checked your codes? Key on-off three times. The cel will flash with the codes. Keep in mind that HO MJ’s aren’t very common here. You may want to also reference XJ/YJ threads for comparison Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted October 13 Share Posted October 13 @acfortierYou may have already read this but here is a thread on how to read the codes and what they mean. Link to comment Share on other sites More sharing options...
acfortier Posted October 13 Author Share Posted October 13 11 hours ago, ghetdjc320 said: Have you checked your codes? Key on-off three times. The cel will flash with the codes. Keep in mind that HO MJ’s aren’t very common here. You may want to also reference XJ/YJ threads for comparison 8 hours ago, Eagle_SX4 said: @acfortierYou may have already read this but here is a thread on how to read the codes and what they mean. Just checked now. Only codes are 12 and 55, which make sense. However, I took another video of the CEL and it is definitely supposed to stay illuminated much longer. Also seems like the MAINT REQ light is supposed to go out at the same time? https://drive.google.com/file/d/1E6N1foVjDRovtaQNUhsePgGBMVu39vnK/view?usp=sharing I assume the ECM controls the CEL directly, so now I'm thinking it's a faulty ECM again? Link to comment Share on other sites More sharing options...
acfortier Posted October 13 Author Share Posted October 13 Found this thread that identifies the same problem: https://www.cherokeeforum.com/f2/check-engine-lamp-259881/ Unfortunately the OP didn't give an update and it's over 10 years old... lol Similar symptoms in this thread: https://www.jeepforum.com/threads/no-check-engine-light-when-key-is-on.603033/ which also mentions a potential faulty ECM. Link to comment Share on other sites More sharing options...
acfortier Posted October 17 Author Share Posted October 17 Replaced the ECU with an eBay unit today. Interestingly, my unit did not have a sticker on the top that has the part number, and the plug itself was orange rather than gray on the replacement. That is the original one in the vehicle. Doesn’t look too great, I think that is a cap next to the heat sink that looks like it’s rusted? Anyways, new ECU in and has been running for 5+ min and got up to temp, no issues so far. The MAINT REQD light is now illuminated which is going to bug me, lol. Link to comment Share on other sites More sharing options...
acfortier Posted October 19 Author Share Posted October 19 OK, short trip to Walmart yesterday, 40 mi round trip today, and no issues. I think it's resolved! Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted October 19 Share Posted October 19 If you want to know the number of the computer clean off the epoxy at the sight I drew around the number is on the chip. A damp paper towel works well. Link to comment Share on other sites More sharing options...
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