86customanche Posted December 1, 2012 Share Posted December 1, 2012 I know that my 98 xj is different from all mjs, but i know a lot of yall have xjs and know a lot so I'm going to put my story about the xj problems I'm having here as well as a couple other forums. This might get long but bear with me. I’m having problems with my 98 xj 4.0. Multiple problems and would appreciate any help y’all could give me. Just as a little background, I replaced the head gasket a couple months ago and drove it on a 300 mile roundtrip in a weekend. The only CEL code I get is P1694. I try to clear it, but that doesn’t seem to work. About a month ago, the battery was completely dead. I charged it overnight and nothing happened so I went and bought a brand new one. Jeep started up just fine. I was out of town for a few days and when I came back about a week later, the battery was dead again. I did a parasitic drain test and the fuse is F22 under the hood, amp meter showed 1.6amps. Removing the fuse reduced the current draw to very little. A chart shows this fuse is the fuel pump relay. Not sure where to start to look because when I bypass the actual relay by connecting pins 30 & 87, the pump runs. Fuse 11 in the junction box is good. just to break up the story a little :banana: The second issue is that it doesn’t start. Even with a fully charged battery (12.6v) it will crank but never starts, and I can’t hear the fuel pump running. I haven’t checked for spark because I’ve already pulled the CPS thinking it was bad. Ran a resistance test on the CPS and between B and C got about 16k ohms on the 20k ohm setting. Not sure if that means it works or not, especially because that test isn’t always conclusive. The fuel and voltage gauge do not move when the key is turned, with or without the CPS installed. Also, when I turn the key to on (not start) I would expect to hear the fuel pump turn on to get some fuel to the rail, and I don’t hear anything. Link to comment Share on other sites More sharing options...
danbyrambler Posted December 1, 2012 Share Posted December 1, 2012 Lots of XJ help here on CC and at NAXJA - - NORTH AMERICAN XJ ASSOCIATION - - - - www.naxja.org Link to comment Share on other sites More sharing options...
Alexia Posted December 1, 2012 Share Posted December 1, 2012 P1684 - Battery Disconnected Within Last 50 Starts - Just a tell tale code for emissions inspection to catch people trying to clear codes by disconnecting the battery. If you are getting a slight draw with that relay hooked up it sounds like the relay is bad. Toss a spare relay in from another, such as the AC fan, to diagnose. Link to comment Share on other sites More sharing options...
86customanche Posted December 1, 2012 Author Share Posted December 1, 2012 edit: the code was p1694. i mistyped. Link to comment Share on other sites More sharing options...
86customanche Posted December 1, 2012 Author Share Posted December 1, 2012 If you are getting a slight draw with that relay hooked up it sounds like the relay is bad. Toss a spare relay in from another, such as the AC fan, to diagnose. still get a draw when the relay is removed. About 1.6 amps Link to comment Share on other sites More sharing options...
dave92cherokee Posted December 1, 2012 Share Posted December 1, 2012 Ok so to clarify fuse 22 in the pdc under the hood is the culprit causing there to be a 1.6A draw on the battery when the xj is off correct? You say that removing the fuse causes the battery drain to drop to very little current draw which is a good sign. That fuse only goes to 2 places, it goes to the fuel pump relay which then passes power to the fuel pump being that wire is the side of the relay that gets switched instead of powering the relay. The other place it goes is to the PCM when it splits off at the connector for the relay. Fuse 11 in the junction block simply powers the fuel pump relay and that's it. Since you said that there's still a drain with the relay removed sounds like you've got a jacked PCM. Link to comment Share on other sites More sharing options...
86customanche Posted December 2, 2012 Author Share Posted December 2, 2012 That makes sense. What/where is the PCM? Ive always hated the electrical part of vehicles. Link to comment Share on other sites More sharing options...
Alexia Posted December 2, 2012 Share Posted December 2, 2012 That makes sense. What/where is the PCM? Ive always hated the electrical part of vehicles. Left side of the vehicle next to the air box with the three big plugs. Link to comment Share on other sites More sharing options...
dfreeman616 Posted December 2, 2012 Share Posted December 2, 2012 Did a quick search on that P1694 code, shorted 5 volt reference, on a tech site from work, found this: Crank no start. Gauges inop. Code P1694. Followed lead on checking for 5V ref on orange wire. Found there was only .5V. Began unplugging sensors but voltage never came back up. Did wiggle test along wire but voltage still didn't change. Cut orange wire about a foor out from the ECM to remove any possible shorted sensors or wires and found there was still only .5V showing the ECM is bad. Orange wire mentioned is the sensor reference used by pretty much everything. Basically you'll need to check that wire for 5v. If it doesn't read 5, start unplugging sensors until it does. may end up needing a computer. however, there are also a lot of problems where that code is set by the crank sensor. that you're having issues with f22 makes me suspicious of the pcm. need some good electrical diagrams? i can get them emailed to you if you give me your addy. Link to comment Share on other sites More sharing options...
86customanche Posted December 2, 2012 Author Share Posted December 2, 2012 The volt thing makes sense too. I tested the voltage on the CPS connector (the part on the vehicle side) and it only read about .5 volts. Link to comment Share on other sites More sharing options...
dfreeman616 Posted December 2, 2012 Share Posted December 2, 2012 to clear things up as i write, CPS doesn't mean crank sensor, CKP does. camshaft sensor is CMP. i'd start unplugging other sensors that use the 5 volt ref to see if any are shorting. there's a couple 5 volt ref circuits in that truck, the CKP shares the circuit with the CMP in the distributor, the MAP, and the TPS. Link to comment Share on other sites More sharing options...
86customanche Posted December 3, 2012 Author Share Posted December 3, 2012 Thats what I plan on doing next. Hope to get to it this week. Busy week at work for me. Link to comment Share on other sites More sharing options...
86customanche Posted December 4, 2012 Author Share Posted December 4, 2012 Today's excitement on this effort... The orange wire from the PCM, black plug, pin A17, only shows .5V. This is still true after disconnecting all the sensors I could find. Link to comment Share on other sites More sharing options...
dave92cherokee Posted December 6, 2012 Share Posted December 6, 2012 PM me on the backside with your email addy and I'll send you something to help with the xj. In the mean time I looked through the fsm and the Orange wire from pin A17 is the 5V supply line. It connects to the crank sensor, cam sensor, oil pressure sensor, map sensor, and throttle position sensor. If you unplug all of those at the same time and still only measure .5V on the line then the PCM is bad as it's not putting out the 5V. If that is the case then I would suggest looking on NAXJA and searching for how to test each sensor to make sure the sensor is good and it won't short out a replacement pcm. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted December 6, 2012 Share Posted December 6, 2012 At my dealership service shop, we have had three dead 4.0L WJ's come in in the last few days with this same issue, and in each case, it was a shorted Crank sensor, pulling down the 5 volt circuits essentially killing the PCM. The first one has had me pulling my hair out trying to figure it out since last week. I had no idea a 5 volt ref circuit shorted out would bring down the whole PCM causing no communication. Lost my but on that job, but learned a lot! Link to comment Share on other sites More sharing options...
86customanche Posted December 6, 2012 Author Share Posted December 6, 2012 At my dealership service shop, we have had three dead 4.0L WJ's come in in the last few days with this same issue, and in each case, it was a shorted Crank sensor, pulling down the 5 volt circuits essentially killing the PCM. The first one has had me pulling my hair out trying to figure it out since last week. I had no idea a 5 volt ref circuit shorted out would bring down the whole PCM causing no communication. Lost my but on that job, but learned a lot! If you don't mind me asking, what was shorted out about the crank sensor. And how could I test that? Link to comment Share on other sites More sharing options...
dave92cherokee Posted December 6, 2012 Share Posted December 6, 2012 The email I sent you will go into detail how to test everything but here's a link to naxja that i found that talks about how to test the cps. Link to comment Share on other sites More sharing options...
86customanche Posted December 6, 2012 Author Share Posted December 6, 2012 :hmm: don't see a link anywhere Link to comment Share on other sites More sharing options...
dasbulliwagen Posted December 6, 2012 Share Posted December 6, 2012 The crank sensor was shorted internally. Not sure how. Didnt test it. Just knew that when it was unplugged, everything came back to life. No sense in wasting time testing the sensor itself when you know it is bad. I'm sure if I looked into it, I would be able to tell you what to do, but as was just posted, that has been covered many times in other places. Let us know what you figure out! Link to comment Share on other sites More sharing options...
86customanche Posted December 6, 2012 Author Share Posted December 6, 2012 What you explain there tells me its not my crank sensor. Nothing changes when I unplug it. The gauges still don't turn on (volt and fuel) and everything else acts the same. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted December 6, 2012 Share Posted December 6, 2012 Unplug all sensors that tie to the 5 Volt ref circuit. I had it all wrote down yesterday but can't find it now. They included the crank sensor, the map sensor, the cam sensor, throttle pos sensor, trans solenoid at the trans, and AC pressure transducer. Unplug all those, then backproble the 5 volt circuit at the PCM with the key on and measure voltage. If you have 5 volts, you have a sensor issue, if you don't have 5 volts, either the PCM is bad or there a short in the wiring. Pull back some of the covering going to the PCM connector, and cut the 5 volt wire a few inches out. Then recheck the 5 volts with the key on. If you have 5 volts then, the PCM is OK and the wire is shorted somewhere. If not, the PCM is bad. Recheck your wiring diagrams as to which and how many items are on the 5v circuit as your may be different. The 04 WJ I worked on had 2 5v circuits coming out of the PCM in different connectors, and the one bad sensor pulled them both down. Just make sure youre covering all bases and let us know what you find. Oh! And after cutting the wire after diag, youll need to repair it. Link to comment Share on other sites More sharing options...
dave92cherokee Posted December 7, 2012 Share Posted December 7, 2012 http://www.naxja.org/forum/showthread.php?t=1091389&highlight=test+cps Sorry there's the link to it I copied it in the post yesterday but it didn't show up. I also noted in that post that the 5v goes to the cam sensor, oil pressure sensor, crank sensor, MAP sensor, and throttle position sensor. Any one of them could have gone south and blown the 5v circuit in the PCM. I would suggest looking around on naxja on how to test each one of those as any of them could be the culprit that caused the problem. Link to comment Share on other sites More sharing options...
86customanche Posted December 8, 2012 Author Share Posted December 8, 2012 I disconnected most of the sensors and pin 17 (orange wire) continues to only carry 0.5V. So I cut the wire about a foot from the PCM, and it still only shows 0.5V, with the key on. Based on a few other postings, I feel a new computer is needed. Does a 98 require the programming of the VIN and mileage? What is a good source for them? Also, there is resistance between pin B&C on the crank position sensor, i.e. not "infinite resistance". Based on a few other postings, I feel a new sensor is needed. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 8, 2012 Share Posted December 8, 2012 Nope, plug and play. What is the part number on that ecu....i have a bunch of them. Link to comment Share on other sites More sharing options...
86customanche Posted December 8, 2012 Author Share Posted December 8, 2012 Nope, plug and play. What is the part number on that ecu....i have a bunch of them. Chrysler P/N P56041 534AF I found a bunch of sites selling reman units, all stated the VIN was required, and all had horrible reviews. Sigh, what a pain this issue has become. Link to comment Share on other sites More sharing options...
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