After lift DW + CEL + GEN + No spark = ???
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After lift DW + CEL + GEN + No spark = ???
Hello All,
To say the least, I have a problem with my son's 1996 XJ Country. We recently added a 3 inch Rough Country lift kit. After we finished up, took it for a ride and we gained a severe DW. I know we have a lot of work to do on the suspension, and the lift made it very apparent. I know well the whole list of items I need to check for on the DW. But first, the problem that we have to deal with is that it has the CEL and the GEN light, as well as no spark to the plugs. Just before I got the Jeep stopped the engine died and could not get it started again; had to tow it home. I used my handy-dandy spark checker from Harbor Freight. I swapped out the battery with a known good one from my 1991 XJ because all the shaking caused some of the electrolyte to spill out. I did get good fuel pressure at the rail. My initial reaction is that the PCM got shaken to death. I pulled it out, and the connectors are corrosion free. I have some electronics experience, so I intend to pull it apart to see what is going on inside. Now that you have the two-cent tour, what do you think? I have been lurking around here for a good long time, so I know of the vast experience that I am trying to draw from. Thanks for your time.
To say the least, I have a problem with my son's 1996 XJ Country. We recently added a 3 inch Rough Country lift kit. After we finished up, took it for a ride and we gained a severe DW. I know we have a lot of work to do on the suspension, and the lift made it very apparent. I know well the whole list of items I need to check for on the DW. But first, the problem that we have to deal with is that it has the CEL and the GEN light, as well as no spark to the plugs. Just before I got the Jeep stopped the engine died and could not get it started again; had to tow it home. I used my handy-dandy spark checker from Harbor Freight. I swapped out the battery with a known good one from my 1991 XJ because all the shaking caused some of the electrolyte to spill out. I did get good fuel pressure at the rail. My initial reaction is that the PCM got shaken to death. I pulled it out, and the connectors are corrosion free. I have some electronics experience, so I intend to pull it apart to see what is going on inside. Now that you have the two-cent tour, what do you think? I have been lurking around here for a good long time, so I know of the vast experience that I am trying to draw from. Thanks for your time.
Last edited by craiso; 07-11-2018 at 10:22 PM.
#2
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Simalar problem
Hello All,
To say the least, I have a problem with my son's 1996 XJ Country. We recently added a 3 inch Rough Country lift kit. After we finished up, took it for a ride and we gained a severe DW. I know we have a lot of work to do on the suspension, and the lift made it very apparent. I know well the whole list of items I need to check for on the DW. But first, the problem that we have to deal with is that it has the CEL and the GEN light, as well as no spark to the plugs. Just before I got the Jeep stopped the engine died and could not get it started again; had to tow it home. I used my handy-dandy spark checker from Harbor Freight. I swapped out the battery with a known good one from my 1991 XJ because all the shaking caused some of the electrolyte to spill out. I did get good fuel pressure at the rail. My initial reaction is that the PCM got shaken to death. I pulled it out, and the connectors are corrosion free. I have some electronics experience, so I intend to pull it apart to see what is going on inside. Now that you have the two-cent tour, what do you think? I have been lurking around here for a good long time, so I know of the vast experience that I am trying to draw from. Thanks for your time.
To say the least, I have a problem with my son's 1996 XJ Country. We recently added a 3 inch Rough Country lift kit. After we finished up, took it for a ride and we gained a severe DW. I know we have a lot of work to do on the suspension, and the lift made it very apparent. I know well the whole list of items I need to check for on the DW. But first, the problem that we have to deal with is that it has the CEL and the GEN light, as well as no spark to the plugs. Just before I got the Jeep stopped the engine died and could not get it started again; had to tow it home. I used my handy-dandy spark checker from Harbor Freight. I swapped out the battery with a known good one from my 1991 XJ because all the shaking caused some of the electrolyte to spill out. I did get good fuel pressure at the rail. My initial reaction is that the PCM got shaken to death. I pulled it out, and the connectors are corrosion free. I have some electronics experience, so I intend to pull it apart to see what is going on inside. Now that you have the two-cent tour, what do you think? I have been lurking around here for a good long time, so I know of the vast experience that I am trying to draw from. Thanks for your time.
#3
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Thanks JandDGreens. I saw that sensor under the battery and wondered what it was for. My 1991 XJ does not have one. This Jeep was running normally before we parked it for the lift installation. It sat for about a week while we were getting things together. While my son was working it, he left the hood up with the light on for about a day and a half. Of coarse, the battery went low and would not start the Jeep. We gave the battery a jump and ran it for a while before he took it out and found the DW problem. It had no issues until the first good DW event.
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While we are discussing the battery temp sensor, does anyone have an idea of what the ohmic value would be for the sensor at normal operating temp of the Jeep? One other thing that I forgot to mention is that prior to all of this madness, my Harbor Freight code reader has never been able to 'link' with this Jeep. That is why I am guessing at what may be causing the CEL and GEN lights. I have pulled and cleaned the grounds at the PCM.
Last edited by craiso; 07-12-2018 at 08:47 AM.
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The code scanner is probably ODB2, and the jeep is OBD1. You can use the key trick to read the codes. Turn the key off and on 3 times and count the check engine light flashes.
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Thanks Geek. This jeep seems to have a random mix of pre-'96 and post-'96 wonderfulness... JandDGreens, my son swapped out the battery temp sensor with one he pulled from my 1998 XJ, no joy. We will try the key jiggle to try reading the codes.
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
The usual death mode for them is a failed cap. They have some electrolytics in there, so opening up might let you see a bad one (swollen, split, or leaking), but other than that, you are not likely to learn anything. If something shorted, you might see a burned trace.
In the highly unlikely event it turns out the be the PCM, fixing it is not realistic. Just buy a new one.
Verify spark (or the absence thereof) and fuel pressure. Also check for 12 into the coil. The spark is generated when the PCM provides ground - the 12v should be constant when the key is on. Same to the injectors. Wouldn't hurt to verify 12v there, too.
Also check yoru battery cables. All four. Yes, four. B+ to the PDC and to the starter. B- to the block and to the inner fender wall. The PCM grounds on the same plate as the B- to the block. Get rough - yank pull push. You are trying to expose any hidden problems. If it's corroded and barely holding on, you want to break it so you know to fix it.
Also investigate your ASD relay. It controls spark, injectors, and fuel pump.
Last edited by BlueRidgeMark; 07-12-2018 at 09:30 PM.
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LadyKenai, we got the key dance to work. Unfortunately, the jeep gave us 12-55. In other words...nada. BlueRidgeMark, I will not be opening up the PCM. All the fuses have power on both sides on both panels. Last year I made all new cables and the grounds are all in good shape. There is good fuel pressure at the rail, but no spark. Gave the battery a good charge. Currently, when the engine cranks the CEL is on. The GEN light goes out after a few cranks, but the engine does not start. We will be checking out the coil today. Something of note, as the engine is cranking the distributor has a slow wobble to it. This is with the cap on. I took the cap off to check it out and the rotor is solid and undamaged.
Last edited by craiso; 07-13-2018 at 08:53 AM.
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
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Could be your cam sensor. If the distributor bearing (bushing?) is shot, it can wipe out the cam sensor. It's under the rotor.
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BlueRidgeMark, as the engine cranks I can smell fuel. I understand that the CMP is involved in fuel injection and dwell. Would this indicate that the CMP is working and allowing the injectors to function? I have replaced the distributor on my '91 that fixed an intermittent shutdown problem. I believe the CMP was bad on that one.
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
CAMSHAFT POSITION SENSOR—PCM INPUT
A sync signal is provide by the camshaft position
sensor located in the distributor (Fig. 3). The sync
signal from this sensor works in conjunction with the
crankshaft position sensor to provide the Powertrain
Control Module (PCM) with inputs. This is done to
establish and maintain correct injector firing order.
Refer to Camshaft Position Sensor in Group 8D,
Ignition System for more information.
A sync signal is provide by the camshaft position
sensor located in the distributor (Fig. 3). The sync
signal from this sensor works in conjunction with the
crankshaft position sensor to provide the Powertrain
Control Module (PCM) with inputs. This is done to
establish and maintain correct injector firing order.
Refer to Camshaft Position Sensor in Group 8D,
Ignition System for more information.
- It's dead, Jim. Nothing. No output. I don't think you'd get fuel into the engine at all.
- Timing is somehow off. Yes, you get fuel, but at the wrong time.
I'm just wondering if something like that could be going on. Can't hurt to pop the top off the distributor and take a look.
#15
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First would be to check the ASD fuse in the PDC (under hood fuse box). If there is no voltage on that fuse, my first thought would go to the CPS having been damaged during the shaking (connectors, harness, or the sensor itself). If I -did- find voltage on that fuse, I would follow it down and see if it was getting to the coil. If I found it going into the coil, but not coming out the other side, I would turn my attention to the possibility that the coil was somehow damaged by the shaking. (heat and vibration are the things that coils and CPS sensors don't get a long with).
I have a scope, so if I suspect the CPS, I would use my scope to see if it had an appropriate signal coming out of it. Without a scope, it can be difficult to troubleshoot definitively. Sometimes for DIY, the easiest thing is to swap it with a known-good part. Also, CPS sensor needs to ride very close to the fly wheel to measure it, so violent shaking of the motor could possibly knock it out of position just slightly, and if it was already on the edge, that could push it over.
These things aren't for-sure but they are what I would suspect first.
I have a scope, so if I suspect the CPS, I would use my scope to see if it had an appropriate signal coming out of it. Without a scope, it can be difficult to troubleshoot definitively. Sometimes for DIY, the easiest thing is to swap it with a known-good part. Also, CPS sensor needs to ride very close to the fly wheel to measure it, so violent shaking of the motor could possibly knock it out of position just slightly, and if it was already on the edge, that could push it over.
These things aren't for-sure but they are what I would suspect first.