Cranks, fires, but won't start...

[crooner]

hey guys, I'm hoping someone has been through this before, I'm stuck.

 

My '95 2-door XJ will crank and start, but die immediately. I can hear the fuel pump as it normally does. It's not (yet) a Comanche but I am seeking a donor truck...so I am hoping someone could help here (posted in CherokeeForum too).

 

Headlights work, dome light works, horn and dash lights work. Windshield wipers (front only) and blower/fan do not work. I checked all the fuses and looked at the relays for failed signs. No luck there.

 

Pulled the blower fuse from the blow and the A/C relay from the PCM. Same thing. Disconnected the battery in case a wayward relay was stuck..ok, that was a real guess.

 

Any thoughts on the crank position sensor being the culprit? Picked one up from NAPA today, $107!! If I install it, I own it. Thought I'd check here first.

[Eagle]

If the problem was the CPS it wouldn't fire at all. If you are certain the fuel pump runs when the key is in the RUN position, that should eliminate the ballast resistor as the problem. I would look next at the ignition switch. However, I think first, just to be certain, I would jumper the ballast resistor to make absolutely sure that's not the problem.

 

A '95 has OBD. Do you know anyone with a scanner that can read '95 Chrysler codes?

[HOrnbrod]

Try running the codes on your OBDI as below. Might give you a starting indication:

 

Reading Computer Codes

 

On 1991 to1997 models you have a way of reading for fault codes which can be accessed without any scanners like other models by reading how the check engine light flashes. Start by turning the ignition key to the last stop before it starts, on and off three times within 5 seconds ending in the on position on the third time, ( i.e. on, off, on, off then on and hold ). The check engine light will start to flash quickly with a small pause in between then a medium pause to indicate the next number in the to digit number and then a long pause before the next set of flashing for the next code. If all is well you will get a code 55 which would read like this: 5 fast flashes, medium pause then a further 5 flashes. This is how all codes end with is this 55 code if you have air conditioning or with a code 33 without and any other codes would have been before it separated by a long pause. The codes will remain after this test so you can cycle through it as many times as it takes to read them. After a problem has gone the code will be removed after 50 on off key cycles or if the battery left disconnected over night which will cause a code 12 though.

 

 

Code

Description

Most likely reason

 

11

No crank signal to computer.

Fault in wiring between crankshaft position sensor (CPS) and ECM ( PCM or computer ) or faulty CPS.

 

12

Battery disconnected.

Battery or power to the ECM disconnected in the last 50 key cycles.

 

13

MAP Sensor.

No change in Manifold Absolute Pressure (MAP) between engine off and on. Check circuit and MAP sensor.

 

14

MAP Sensor.

MAP sensor voltage too high or low. Check circuit and sensor.

 

15

Speed sensor or circuit.

No signal detected from speed sensor. Check circuit and sensor.

 

17

Engine running too cold.

Wrong or faulty thermostat. Check also sensor and circuit for fault.

 

21

Oxygen sensor or circuit.

O2 sensor or wiring faulty.

 

22

Coolant sensor or circuit.

Check temp sensor and wiring.

 

23

Intake air temp or circuit.

Check air temp sensor and wiring.

 

24

Throttle Position Sensor (TPS)

Check TPS sensor and wiring.

 

25

Idle Air Control circuit (IAC)

Check IAC sensor and wiring.

 

26

Injector circuit resistance.

Peak injector current has not been reached or injector circuits have resistance

 

27

Fuel injector control circuit.

Will need specialist diagnostics.

 

31

Evaporative control circuit.

Fault in fuel evaporative control circuit or hoses.

 

33

Air conditioning clutch relay.

Wiring to A/C clutch fault.

 

34

Cruise control circuit.

Fault in circuit.

 

35

Cooling fan relay.

Check relay and circuit.

 

36

Air switch solenoid circuit.

Air switch solenoid circuit (non-turbo) or the waste gate solenoid on turbocharged models

 

37

Torque converter clutch.

Needs specialist or dealer diagnostics.

 

41

Alternator field switch.

Switch not operating correctly and check charging system.

 

42

Automatic shutdown relay.

Check relay and circuit. Needs specialist or dealer diagnostics.

 

43

Misfire.

Misfire in one or more cylinders.

 

44

Battery temperature sensor.

Needs specialist or dealer diagnostics.

 

46

Battery over voltage.

Check charging system.

 

47

Battery under voltage.

Check charging system.

 

51

O2 detects lean mixture.

Check sensor and circuit and for vacuum leaks.

 

52

O2 detects rich mixture.

Check fuel injection system and sensor.

 

53

Powertrain Control Module.

PCM (ECM) fault. Needs specialist or dealer diagnostics.

 

54

Distributor sync pickup.

Change sync sensor in distributor.

 

55

End of code.

Trouble codes finished or none recorded.

 

61

BARO solenoid

BARO solenoid failure

 

62

Emissions reminder.

Emissions maintenance reminder. Needs specialist or dealer diagnostics.

 

63

Controller failure.

EEPROM write denied. Needs specialist or dealer diagnostics.

 

64

Flexible fuel sensor.

Flexible fuel (methanol) sensor indicates concentration sensor input more/less than acceptable voltage

 

65

Manifold tune value.

Manifold tune valve solenoid circuit open or shorted

 

66

TCM to PCM failure.

No message from the Transmission Control Module (TCM) to the Powertrain Control Module (PCM)

 

72

Catalytic converter circuit.

Needs specialist or dealer diagnostics.

 

76

Fuel pump bypass relay circuit.

Needs specialist or dealer diagnostics.

 

77

Cruise control system.

Check power to cruise control solenoids.

[crooner]

This issue is keeping me up at night, since my only other mode of transport is my old motorcycle! So, this is a huge help guys, thanks. :clapping:

 

I read about bypassing the ballast resistor, but figured it was getting fuel since I got spark. That maybe a bad assumption, so I'll do that test. IIRC the ballast resistor is on the driver's side in the engine compartment. TO be clear though, the starter engages as it should and it begins to start as usual--so I let off the key at that point, but after the starter spins the flywheel...it just stops. So, is that more likely the CPS failing or no fuel?

 

I do not know anyone with a scanner, so I'll try the ignition switch on/off method--this assume that the switch is not the problem though, yes?

 

Maybe I'll look for a reasonably priced scanner too--not a bad thing to have, I'd guess.

 

On some of the diesel forums I belong to, they have a section set up for folks with scan tools to sort of 'register' what they have, where they are located and how much time needed to get the tool (in case its a work tool). Most folks/enthusiasts offer to help for free or a modest compensation (er, beer, lunch, etc.). One guy went as far as to produce a Google map with tool locations based off the guys that registered their scanners in the section...not sure everyone wanted to be mapped like that though.

[Eagle]

I read about bypassing the ballast resistor, but figured it was getting fuel since I got spark. That maybe a bad assumption, so I'll do that test. IIRC the ballast resistor is on the driver's side in the engine compartment. TO be clear though, the starter engages as it should and it begins to start as usual--so I let off the key at that point, but after the starter spins the flywheel...it just stops. So, is that more likely the CPS failing or no fuel?

The CPS controls the ignition, and the injection pulse. If the CPS were the problem, it would not start. Not at all. If you have spark, the problem is not the CPS.

 

Assuming you have fuel because you have spark is a VERY bad assumption. The CPS does not in any way control or affect the fuel pump. But the ballast resistor does. The ballast resistor reduces voltage to the fuel pump during running. For starting, the start circuit bypasses the ballast resistor so you get the full 12 volts to the fuel pump. Which means the fuel pump will pump as long as the key is in START because the circuit bypasses the ballast resistor, but when the key is released to the RUN position the bypass circuit goes away and the power to the fuel pump goes through the ballast resistor. If that's bad, the fuel pump stops pumping as soon as the key goes to RUN, and the engine dies as soon as the residual fuel in the system has been used up.

[crooner]

Ok, thanks for that explanation. To be clear, it is not starting at all. It turns over like it normally does and at the point where I let off the key (back to the RUN position) it dies. From your explanation, it certainly stands to reason that the ballast resistor is the issue...however...

 

I stopped by the local Jeep dealer and they could not find a ballast resistor for my Jeep. I compared the Haynes and Chrysler Jeep manual to my engine compartment and can't find anything even closely resembling the resistor. It shows it being on a bracket near the washer fluid reservoir, but nothing there on mine. Is it possible that the newer Jeeps do not have the resistor? Or would anyone have a picture of one that they could post? The dealer can't even locate the part on any of their diagrams and they all seemed a bit puzzled as to whether or not one existed for the vehicle.

 

...man this is frustrating.

[Eagle]

Ok, thanks for that explanation. To be clear, it is not starting at all. It turns over like it normally does and at the point where I let off the key (back to the RUN position) it dies. From your explanation, it certainly stands to reason that the ballast resistor is the issue...however...

Let's go back to basics.

 

Your opening post says it cranks and it starts, then it dies. That's saying it starts. Now you are saying that it is not starting at all, which would mean it is NOT starting.

 

I don't mean to sound insulting, but do you know the difference between "cranking" or "turning over" and "firing"? It's difficult enough to diagnose problems by remote control with an accurate description of the symptoms. When the description of the symptoms is self-contradictory, it's impossible.

 

Do you have spark, or not?

 

Also, your opening post says you can hear the fuel pump. Is that with the key in the RUN position or in the START position? Because if it's with the key in the RUN position, then the fuel pump IS getting power and the problem is not with the ballast resistor. However, it could be that the fuel pump isn't pushing enough fuel to keep the engine running. If you can hear the fuel pump running when you first turn the key to RUN (not START), does it run for 5 or 10 seconds and then stop, or does it keep running? It should shut off after a few seconds because the fuel rail has pressure. If it doesn't shut off, either the pump is bad or the fuel pressure regulator is bad.

 

According to the '94 XJ FSM, as of 1994 the ballast resistor was no longer used, so that was a bad call on my part. You can stop looking for it.

[crooner]

Ok, I too discovered that the ballast resistor was stopped in 1994, so I stopped searching. No harm.

 

I guess I am not describing the problem accurately. I do know the difference between cranking and starting, but probably wasn't clear about what's happening. Here is what I've confirmed:

 

1.) Turn the key to RUN, I heard the fuel pump run for a few seconds (as normal). Tonight, I disconnected the fuel supply side and placed it on a clean rag to confirm that I am getting fuel. I turned the key to RUN, listened for the fuel pump to run then stop and finally, cranked it. Plenty of fuel is being pumped.

 

2.) No check engine light doing the on/off/on/off/on method.

 

3.) Ballast Resistor not used on 1994 and newer, mine is a 1995.

 

4.) When I crank the engine, it sounds normal and like it is about to catch (start), so I release the key back to the RUN position and the engine dies (or never really starts). You can hear it firing though when it is cranking--this is probably where I confused the description. The engine never really starts and runs on its own.

 

5.) When all this happened, the blower motor (AC/fan) stopped working as did my front (only) windshield wipers. I was completing a 1300 mile trip and had noticed that the volt drain with the fan running (on AC or just vent) was a pretty strong draw. Not sure why the windshield wipers stopped too though but am considering the possibility that the whole issue COULD be in the ignition switch in the steering column (yikes).

 

6.) Tonight, I pulled the blower motor and bench tested it. Works just fine. Still, I pulled the blower motor fuse to eliminate a potentially high draw that may be confusing a relay, etc. With the blower motor out of the Jeep, I tried to start it again--same results and no wipers still.

 

7.) Pulled all fuses in the kicker panel under the drivers side of the dash, none blown. Did the same to the PMC and all good.

 

8.) I have still NOT installed the crank position sensor (CPS), that's tomorrow's project.

 

9.) Headlights, dashlights, turn signals, flashers, rear wiper and dome lights all work. This truck does not have a radio hooked up, and nothing that I would think would pull any juice from the battery, but when I reconnect the battery (key OFF), there is a tiny spark on the negative cable.

 

All this happened as I returned from a long trip, and fortunately (without thinking anything other than the blower motor had gone) in my barn, in the lift bay. That's about best news of the whole thing.

 

So, if it turns out to be the CPS, what in the WORLD does that have to do with the front wiper and blower/fan motor? I guess I need to confirm that I have spark now...although I drove it into the barn, as normal. About the only thing that happend since I last successfully started it was that when I turned off the blower motor it would not restart (I did that on my drive home).

 

Off the beaten path thoughts:

- Distributor (which has been chirping a bit) could have died. Not sure how to test that. hmmm

- Blower motor resistor crapped out, resulting in possible high current draw and throwing off red herring symptoms

- Ignition switch died

- Ignition switch post misaligned such that its not making 'RUN' contact

[Eagle]

Did you check for fault codes as described by Hornbrod?

[crooner]

Update: Before attempting to install a new CPS, I disconnected the old one and tried starting it to see how it sounded. As you guys said, it will not fire. Since it begins to fire when the CPS is plugged in, I am guessing the CPS is not the problem.

 

I pulled each fuse in the relay box (on the passenger side of the engine) and verified continuity. I had the negative battery terminal disconnected and checked for resistance on each fuse socket. The 15amp tiny ignition fuse shows 2.5 ohms resistance. The large 60amp ignition fuse socket shows none.

 

Maybe I am way off, but I think this points to either the ignition switch or an issue in the fuse box (PCM I think its called).

 

Also pulled the blower fan and bench tested it, all ok. Pulled the fan resistor and it was heavily rusty likely from the AC condensation that used to build up and dump in the front foot wells until I discovered the clogged drain tube and remedied that. That may have caused the short of the blower...still baffled though.

[HOrnbrod]

I pulled each fuse in the relay box (on the passenger side of the engine) and verified continuity. I had the negative battery terminal disconnected and checked for resistance on each fuse socket. The 15amp tiny ignition fuse shows 2.5 ohms resistance. The large 60amp ignition fuse socket shows none.

 

Maybe I am way off, but I think this points to either the ignition switch or an issue in the fuse box (PCM I think its called).

 

Reading the resistance across fuse terminals w. the negative mains cable removed from the battery tells you nothing unless you have the FSM opened to that particular circuit and follow it from one fuse terminal to the other through each component. I'm guessing you didn't do this. :roll: You could be reading through a relay coil or NC contacts, a resistor, through the ECU, a diode, or just reading corrosion resistance through a connector. It doesn't point to anything - sorry. Did you do the fault code test correctly? I can't believe you had none.

[Eagle]

The fuse box is not the PCM. PCM is the acronym for Powertrain Control Module -- i.e. the computer.

 

Did you read the diagnostic codes or not?

[HOrnbrod]

PDC: Power Distribution Center. Relay module, right side of engine compartment, 91+ HOs

ECU: Engine Control Module. Usually refers the the 91-95 XJ/MJ OBDI models

PCM: Powertrain Control Module. Usually refers to the 96-01 XJ/MJ OBDII models

 

:thumbsup:

[crooner]

The fuse box is not the PCM. PCM is the acronym for Powertrain Control Module -- i.e. the computer.

 

Did you read the diagnostic codes or not?

 

Ok, sorry I got the acronyms wrong.

 

I refer to the fuse panel as the one under the driver's side footwell.

I know where the computer is, driver's side in the engine compartment near the air filter box.

The box that houses the relays (AC, starter, etc.) in the engine compartment on the passenger side just aft of the battery is what I was errantly calling the PCM--that's the box I've been focusing my time on.

 

I did the key on/off/on/off/on and no codes, meaning no check engine light flashing, in fact its never come on except when I go to start the engine as normal. Should the 55 code flash on an otherwise properly running engine as an indication of no error codes?

[crooner]

PDC: Power Distribution Center. Relay module, right side of engine compartment, 91+ HOs

ECU: Engine Control Module. Usually refers the the 91-95 XJ/MJ OBDI models

PCM: Powertrain Control Module. Usually refers to the 96-01 XJ/MJ OBDII models

 

:thumbsup:

 

By 'right side of the engine compartment', you mean the passenger's (starboard) side, yes?

[Automan2164]

Yes, the 55 code should appear.

 

Rob L.

[HOrnbrod]

By 'right side of the engine compartment', you mean the passenger's (starboard) side, yes?

 

Si, starboard side. :cheers:

[crooner]

Did you do the fault code test correctly? I can't believe you had none.

 

Perhaps not. I turned the key from the OFF position to RUN, back to OFF, back to RUN, back to OFF then back to RUN and let it sit like that for over a minute. Is that the correct way to do it?

 

BTW, ordering the FSM tomorrow morning...but I need to start a new job 600 miles away on Aug 9th and would like to get there with my once trusty steed.

[crooner]

Yes, the 55 code should appear.

 

Rob L.

 

Hmmm...so I'll chalk that up as another thing that got fried or whatever unless I am not triggering the diag codes correctly.

 

The list, thus far is:

 

Engine cranks, fires then nada

Engine error codes not displaying.

Blower motor (haven't checked the switch yet, that's next)

Front wipers

[HOrnbrod]

Perhaps not. I turned the key from the OFF position to RUN, back to OFF, back to RUN, back to OFF then back to RUN and let it sit like that for over a minute. Is that the correct way to do it?

 

Yes, that's correct. You'll get the 55, then if there are any fault codes stored, they will come next in order, then another 55 end it all. Just for kicks and grins, unplug the ECU, inspect the pins for any that are recessed or bent, spray a little contact cleaner on the connector pins, then plug it back in again. And make sure the ECU connector bolt is tight.

[Lloyd]

I had an issue with my Comanche once that had a similar description. I lost wipers, blower motor and tail lights. It turned out to be the ignition switch that is bolted on the column near the brake pedal. It is controlled by a pushrod from the key cylinder. The plastic cased switch had melted under one contact, so while the others made contact, the particular one for those componets was not making good contact. But it made good enough for some things to work with albeit lower voltage. It was strange and hard to diagnose, but I was able to tell it was the problem by turning the key on and the blower switch in a run position and then squeezing the column mounted switch with my hand around it and the column. Then the blower would come on until I released the grip.

[crooner]

I had an issue with my Comanche once that had a similar description. I lost wipers, blower motor and tail lights. It turned out to be the ignition switch that is bolted on the column near the brake pedal. It is controlled by a pushrod from the key cylinder. The plastic cased switch had melted under one contact, so while the others made contact, the particular one for those componets was not making good contact. But it made good enough for some things to work with albeit lower voltage. It was strange and hard to diagnose, but I was able to tell it was the problem by turning the key on and the blower switch in a run position and then squeezing the column mounted switch with my hand around it and the column. Then the blower would come on until I released the grip.

 

Headed back to the barn to try that.

 

I've ruled out the following:

 

1.) CPS, since it fires/sparks like it normally does but dies immediately. If I doconnect the CPS wire, no spark.

2.) Auto Shut Down relay. Swapped it for a new one today, no joy.

3.) Fuel pump and pump circuit--if you could have smelled the barn after I took the supply side off and cranked it!

4.) Disconnected the MAP sensor, sprayed contact cleaner, reconnect. No joy there either.

 

Blinkers, flashers work when key in RUN position, so I think its making proper contact. However, blower, front wipers and the cigarette lighter do not work when the key is in the RUN position. Blower motor checked out ok on the bench and I installed a new blower motor resistor. Non-switched things work, like the horn, headlights, dome lights, etc. Oddly, the rear wiper does work. Haven't checked the tail lights, but I'll look at the column mounted iggy switch.

 

Might also try to start it in neutral, although if the neutral safety switch were bad, wouldn't the blower and wipers work in the RUN position anyway? I dunno.

 

Thanks!

[crooner]

Perhaps not. I turned the key from the OFF position to RUN, back to OFF, back to RUN, back to OFF then back to RUN and let it sit like that for over a minute. Is that the correct way to do it?

 

Yes, that's correct. You'll get the 55, then if there are any fault codes stored, they will come next in order, then another 55 end it all. Just for kicks and grins, unplug the ECU, inspect the pins for any that are recessed or bent, spray a little contact cleaner on the connector pins, then plug it back in again. And make sure the ECU connector bolt is tight.

 

I get nothing blinking at all. I'll check the ECU connector, clean it, etc (located on the 'port' side, this is what I call the computer).

[Eagle]

Might also try to start it in neutral, although if the neutral safety switch were bad, wouldn't the blower and wipers work in the RUN position anyway? I dunno.

If the neutral safety switch were bad, (a) it wouldn't crank at all, and (B) you wouldn't have spark.

[HOrnbrod]

I get nothing blinking at all. I'll check the ECU connector, clean it, etc (located on the 'port' side, this is what I call the computer).

 

Does the CEL illuminate when you turn the key on? It's sounding more and more like an ECU problem to me mate. :eek: