Check Engine Light woes...

[One_Big_Midgett]

Hey folks, The CEL on my 95 came on the other day. I thought it might be cause i was low on oil. I added a quart and GF said it went out. I was not driving it that day. I was busy driving the moving truck. Now after driving for about 10 min it comes on and stays on. If you let it sit for like an hour or so when you start and run it, bout 10 min later light comes back on. Any ideas? And where can I have my codes checked?

[89Laredo]

Cant tell you anything without the codes... Autozone.

Sent from my DROIDX using Tapatalk 2

[One_Big_Midgett]

Cant tell you anything without the codes... Autozone.

Sent from my DROIDX using Tapatalk 2

I will swing by Auto Zone on the way home thanks!!!

[Mudderoy]

Hey folks, The CEL on my 95 came on the other day. I thought it might be cause i was low on oil. I added a quart and GF said it went out. I was not driving it that day. I was busy driving the moving truck. Now after driving for about 10 min it comes on and stays on. If you let it sit for like an hour or so when you start and run it, bout 10 min later light comes back on. Any ideas? And where can I have my codes checked?

Do you have an oil pressure gauge or an idiot light? What's the pressure, or does the idiot light come on?

[nateyz2000]

Can you check your own codes by turning ignition on and off 5 times (quickly) and leaving it in on position, reading the flashes? Or is that an older model only thing?

Nate

[Carves]

This is from the '95 manual ... and might save you a few trips to the auto store ;)

ACCESSING DIAGNOSTIC TROUBLE CODES

A stored diagnostic trouble code (DTC) can be displayed by cycling the ignition key On-Off-On-Off-On within three seconds and observing the malfunction indicator lamp. This lamp is displayed on the instrument panel as the CHECK ENGINE lamp


If the lamp flashes 4 times, pauses and flashes 1 more time, a flashing Diagnostic Trouble Code (DTC) number 41 is indicated.

If the lamp flashes 4 times, pauses and flashes 6 more times, a flashing Diagnostic Trouble Code (DTC) number 46 is indicated.


Not sure whether theres a DTC description list on the forum ... but if you post what DTC you find - here in your thread .... someone will post a description.

[One_Big_Midgett]

Do you have an oil pressure gauge or an idiot light? What's the pressure, or does the idiot light come on?

I have a dummy light, but the light never comes on.

[Mudderoy]

I have a dummy light, but the light never comes on.

I don't know how accurate this is, but searching for 1995 Jeep Cherokee CEL codes I found this...

522 Oil pressure sensor problems
523 Oil pressure sensor problems

That was the only reference I could find for oil pressure. I would think that this wouldn't be a low oil condition but an actual fault with the sensor, wiring, or computer.

[xj4life2]

I would say first things first , to heck with the codes put a guage on that hing and be sure you have proper oil pressure before something bad happens. Then worry about the codes.Jeeps are known for the oil pump going out at 125k plus. This will ruin the motor.AUto Zone and some of the other parts places rent tools , get an external oil pressure guage remove the oil pressure sender and screw in the guage.Here are the specs:
OIL PRESSURE



At Low Speed (600 rpm) 89.6 kPa (13 psi)

At 1600 rpm and Higher 255-517 kPa (37-75 psi)

Oil Pressure Relief 517 kPa (75 psi)

If all this checks out then go for the codes but lets be sure we have a safe engine first.

[89Laredo]

So... You said you were going to get the codes read and didnt.
As Ive mentioned, we cant tell you anything without the codes. So we are pretty much just wasting time and forum space right now.

AFAIK low oil pressure will not turn the cel on, and being a quart low wouldnt drop your pressure enough (or at all) in the first place.

Do the key trick, you just will have to look at blinks instead of LCD display.
97 Cherokee OBDII Key Trick - YouTube

(http://www.youtube.com/watch?v=h4RhmgJcwAY&feature=plcp)Yes, that jeep was a POS.

11* No Crank Reference Signal at PCM No crank reference signal detected during engine cranking.

12* Battery Disconnect Direct battery input to PCM was disconnected
within the last 50 Key-on cycles.

13** No Change in MAP From Start to Run No difference recognized between the engine
MAP reading and the barometric (atmospheric)
pressure reading at start-up.

14** MAP Sensor Voltage Too Low MAP sensor input below minimum acceptable
voltage.
or
MAP Sensor Voltage Too High MAP sensor input above maximum acceptable
voltage.

15** No Vehicle Speed Sensor Signal No vehicle distance (speed) sensor signal detected during road load conditions.

17* Engine is Cold Too Long Engine coolant temperature remains below
normal operating temperatures during vehicle
travel (thermostat).

21** O2S Stays at Center Neither rich or lean condition detected from
the oxygen sensor input.
or
O2S Shorted to Voltage Oxygen sensor input voltage maintained above
the normal operating range.

22** ECT Sensor Voltage Too High Engine coolant temperature sensor input
above maximum acceptable voltage.
or
ECT Sensor Voltage Too Low Engine coolant temperature sensor input below
minimum acceptable voltage.

23** Intake Air Temp Sensor Voltage Low Intake manifold air temperature sensor input
below the minimum acceptable voltage.
or
Intake Air Temp Sensor Voltage High Intake manifold air temperature sensor input
above the maximum acceptable voltage.

24** Throttle Position Sensor Voltage High Throttle position sensor input above the maxi-mum acceptable voltage.
or
Throttle Position Sensor Voltage Low Throttle position sensor input below the mini-mum acceptable voltage.

25** Idle Air Control Motor Circuits A shorted condition detected in one or more of
the idle air control motor circuits.

27* Injector #1 Control Circuit Injector #1 output driver does not respond
properly to the control signal.
or
Injector #2 Control Circuit Injector #2 output driver does not respond
properly to the control signal.
or
Injector #3 Control Circuit Injector #3 output driver does not respond
properly to the control signal.
or
Injector #4 Control Circuit Injector #4 output driver does not respond
properly to the control signal.
or
Injector #5 Control Circuit Injector #5 output driver does not respond
properly to the control signal.
or
Injector #6 Control Circuit Injector #6 output driver does not respond
properly to the control signal.

33* A/C Clutch Relay Circuit An open or shorted condition detected in the
A/C clutch relay circuit.

34* Speed Control Solenoid Circuits An open or shorted condition detected in the
Speed Control vacuum or vent solenoid cir-cuits.
or
Speed Control Switch Always Low Speed Control switch input below the mini-mum acceptable voltage.
or
Speed Control Switch Always High Speed Control switch input above the maxi-mum acceptable voltage.

35*
(XJ Only)
Rad Fan Control Relay Circuits An open or shorted condition detected in the
radiator fan relay circuit.

41** Generator Field Not Switching Properly An open or shorted condition detected in the
generator field control circuit.

42* Auto Shutdown Relay Control Circuit An open or shorted condition detected in the
auto shutdown relay circuit.

44* Battery Temp Sensor Volts out of Limit An open or shorted condition exists in the en-gine coolant temperature sensor circuit or a
problem exists in the PCM’s battery tempera-ture voltage circuit.

46** Charging System Voltage Too High Battery voltage sense input above target
charging voltage during engine operation.

47** Charging System Voltage Too Low Battery voltage sense input below target
charging during engine operation. Also, no sig-nificant change detected in battery voltage
during active test of generator output.

51** O2S Signal Stays Below Center (Lean) Oxygen sensor signal input indicates lean air/
fuel ratio condition during engine operation.

52** O2S Signal Stays Above Center (Rich) Oxygen sensor signal input indicates rich air/
fuel ratio condition during engine operation.

53* Internal PCM Failure PCM Internal fault condition detected.
or
PCM Failure SRI Communications PCM Internal fault condition detected.

54* No Cam Sync Signal at PCM No fuel sync (camshaft signal) detected during
engine cranking.

55* Display not shown on DRB scan tool Completion of diagnostic trouble code display
on the Malfunction Indicator Lamp (Check En-gine Lamp).

62* PCM Failure SRI miles not stored Unsuccessful attempt to update SRI (service
reminder indicator) miles in the PCM EE-PROM.

63* PCM Failure EEPROM Write Denied Unsuccessful attempt to write to an EEPROM
location by the PCM.

* Check Engine Lamp will not illuminate at all times if this Diagnostic Trouble Code was recorded. Cycle
Ignition key as described in manual and observe code flashed by Check Engine lamp.
** Check Engine Lamp will illuminate during engine operation if this Diagnostic Trouble Code was recorded.

[One_Big_Midgett]

Ok if I did this correctly i got 1-22-1-55. So from what I understand the 1 is the divider between the codes and the 55 is the end, so that leaves me with 22. Which according to the list above (Thanks Laredo) a 22 is....

ECT Sensor Voltage Too High Engine coolant temperature sensor input above maximum acceptable voltage.
or
ECT Sensor Voltage Too Low Engine coolant temperature sensor input below minimum acceptable voltage.

Right?

[89Laredo]

There isnt a blink in between, AFAIK.
Ive done it on a 96 and a 97 and they didnt have an extra blink, but those are OBDII and yours is OBDI.
Manual doesnt say anything about it either.
If you have a camera and good internet, throw a video up.

[oderdene]

Ok if I did this correctly i got 1-22-1-55. So from what I understand the 1 is the divider between the codes and the 55 is the end, so that leaves me with 22. Which according to the list above (Thanks Laredo) a 22 is....

ECT Sensor Voltage Too High Engine coolant temperature sensor input above maximum acceptable voltage.
or
ECT Sensor Voltage Too Low Engine coolant temperature sensor input below minimum acceptable voltage.

Right?


it seems 12 21 55,

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

21 Oxygen sensor or circuit. O2 sensor or wiring faulty.

55 End of code. Trouble codes finished or none recorded.

http://jeep-xj.info/HowtoECUcodes.htm

[Carves]

X 2 with ... xj4life2

Deal with the oil light / pressure issue ... Then deal with the CEL.

The computer is primarily tasked with monitoring things that affect emissions ... Its not an improved vehicle control system ... Its a gubberment required, circuit board version - of a long haired, hippie eco-freak ... who's hiding under your hood ... instead of being chained to a tree ...

... and as such ... doesnt really care if you have low compression or the crank bearings are running dry.

FWIW ... The oil light issue might be just a dodgy sender or dirty connector plug ... but verify presures with another pressure gauge for peace of mind.


I'm not exactly '95 model literate - but Im going to upset the applecart and suggest ... maybe the codes are ....

12 ... battery disconnected

21 ... O2 sensor

55 ... End of display

... since its emission issues that normally cause permanent CELs.

So it might be worthwhile cleaning and checking the O2 sensor wiring & connectors ... or replacing them if they have been in the vehicle since it rolled off the production line. ??


edit: ... I type tooooo slow ... :bang:

X2 with oberdene

:D

[89Laredo]

Unless I fail at reading, He never said his oil light was on...

[Carves]

Unless I fail at reading, He never said his oil light was on...


Yes you're right ... :thumbsup:

Looks like I need to clean the computer screen as well as my glasses .. :rotfl2:


So we're back to the codes and the cause of the CEL. ;)

[One_Big_Midgett]

Laredo is correct guys, the oil press light never goes off. Just the CEL. I will try to video it today.

[4.3LXJ]

If you have an oil pressure light not going off, either it is a bad sender or sender unit wire making a ground

[xj4life2]

You said that the oil pressure light never goes off, but then in another post if I read corectly that after adding a quart of oil it went out. I still think an oil pressure check is needed to insure the safety of that motor, If it were here thats the first thing we would do. Next, as for the codes if it is an o2 code, just replace the o2 with a quality o2, thier not that expensive and really should be replaced every 30k on the 4.0. If I remember correctly my owners manual for the 90 said 27k. Steve very well could be correct in the sender or wire being bad, but it could also be the pump not working as it should and by adding the quart it upped the pressure enough to turn out the light. I will also add that a good set of manual guages in the XJ would be a great addition. and also eliminate alot of the guess work.

[One_Big_Midgett]

Video as promised...

http://youtu.be/w3CIL2WUsho

[Mudderoy]

Video as promised...

http://youtu.be/w3CIL2WUsho

Youtube says it's a dup.

[89Laredo]

CEL - YouTube


I see 12 21 55

21** O2S Stays at Center Neither rich or lean condition detected from
the oxygen sensor input.
or
O2S Shorted to Voltage Oxygen sensor input voltage maintained above
the normal operating range.

Do you wheel your jeep? Ive heard of people ripping their oxygen sensor wiring on the driveshaft.

[One_Big_Midgett]

I have not wheeled in quite a while, but now I know what to look at first. Thanks guys!!!!

Just a side note, While I was under Big Nasty looking around I noticed the pan gasket was seeping a bit. So I am going to replace that and then check my pressure. Just for piece of mind.