Cherokee Diagnostic Codes

studmanken · #1 (**permalink**) 08-07-2003, 05:56 PM

Hey all, my check engine light recently came on in my 2000 cherokee. It has 35000 miles on it and has the 4.0L engine. I was reading some of the other posts about the diagnostic codes and they said to check out AutoZone and get a loaner diagnostic computer, however, there are no AutoZones close to me. Is there any other way I can find out what the problem is without paying 60 bucks to a mechanic to tell me? Your help would be appreciated. Thanks!

XJNick · #2 (**permalink**) 08-07-2003, 06:02 PM

Any OBD-II compliant scanner can give you those trouble codes. There may be a way to get them to read on the Check engine light, but either way a scanner is the best way to do it (gives you better info.)

You might consider buying a scanner if you do lots of work on the Jeep

-Nick

Sound_Man · #3 (**permalink**) 08-07-2003, 06:41 PM

Nick,
Is there a way to get the 88's to blink out a code? I know they don't store codes.

XJNick · #4 (**permalink**) 08-07-2003, 10:49 PM

Quote:

Is there a way to get the 88's to blink out a code?

Nope. The cherokees have NO check engine lamp. To my knowledge the only way to check the live status of the computer is through a specialty scanner.

The best you can do without a scanner is use a multimeter to check voltages through the diagnostic connectors. Let me know if you want to know what each pin is for.

-Nick

Sound_Man · #5 (**permalink**) 08-08-2003, 03:50 AM

Drop a schematic in here if ya can ;-)

studmanken · #6 (**permalink**) 08-08-2003, 03:54 AM

Thanks Nick. How much does a scanner run? And know of any good brands or what to look for?

XJNick · #7 (**permalink**) 08-08-2003, 10:52 AM

Hi

Sound Man, I'll have to redraw the picture to post it (or get sued by their source :wink: ). Don't worry, I'll get ya one

studmanken,

I don't own a scanner, so can't really recommend a brand. What you might consider getting are the scanners that plug into a palm or a laptop, they just sound neat!

-Nick

XJNick · #8 (**permalink**) 08-08-2003, 12:02 PM

Here's a picture of the diagnostic connectors (on non OBD-II Jeeps.):

You can used some of the pins in these connectors as testing points for various circuits. DO NOT mess with the ECU RX or TX ports... these are only for serial data transmission and receiving.

-Nick

Sound_Man · #9 (**permalink**) 08-08-2003, 05:59 PM

Nick,

Do you have a list of the nominal or normal range voltage for those connectors as well?

Thanks,
Curt

XJNick · #10 (**permalink**) 08-08-2003, 06:27 PM

Wow, loaded question!

Well, it all depends on what devices are on and/or what mode the computer is in to determine which pins should be hot or not. For example, C2 pin 12 will be hot after the ignition is switched off....

Here are some others (once again some may or may not be hot depending on what's on):

C1 pins 5 and 6 should be 12volts
C2 pins 3,4,6,9,11,12,14 should be 12volts
C1 pin 3 should be 0 volts (ground)
C2 pin 7,8 should be 0 volts (ground)

Alternatively, you should be able to test certain devices through these plugs with the Jeep off. For example, supply 12volts to C2 pin 11 to test the shift lamp. Just be sure to Never put 12 volts to a ground wire or C2 pins 1,2, or 15

Hope that helps you

-Nick

Sound_Man · #11 (**permalink**) 08-08-2003, 06:39 PM

That helps a lot!! Thanks. I am really interested in C2-15. My trans is not shifting where it is supposed to (It goes through 1st, 2nd, and into 3rd and overdrive very quickly) and will not downshift when I romp on the gas. I am in third gear at 25 mph and it will not downshift. the kickdown cable is still attached and I have adjusted it out as far as it goes.

XJNick · #12 (**permalink**) 08-08-2003, 06:55 PM

Well, it appears to me that C2 pin 15 is also a serial data line, meaning only a scanner could read its output. I'm not sure though, since I don't know much about Auto transmissions

.

-Nick

Bounty__Hunter · #13 (**permalink**) 08-09-2003, 03:47 AM

Hold the odometer button in while you switch the ignition from off to run (not start) and back to off. Any stored trouble codes should display in the odometer.

XJNick · #14 (**permalink**) 08-09-2003, 10:34 AM

The 1988 cherokee odometers are not digital :P

-Nick

Bounty__Hunter · #15 (**permalink**) 08-10-2003, 12:38 AM

I know

Talkin' bout the '00 in the original post. Makes it easy to troubleshoot

XJNick · #16 (**permalink**) 08-10-2003, 12:43 AM

Good point

-Nick

limbmkr · #17 (**permalink**) 08-12-2003, 12:18 AM

Hey I do know 1989 Cherokee Laredo 4.0 do have yellow caps (2 of em) Would the Odometer testing work on 1989 since you guys been talking about 1988?? Will test them to see what the voltage looks like shown above.. I assume if I do have yellow caps which should works for 1989..

I will check back later if 1989 is different than 1988..

XJNick · #18 (**permalink**) 08-12-2003, 07:54 AM

Quote:

Would the Odometer testing work on 1989 since you guys been talking about 1988??

No. Bounty was talking about the 2000 model year Jeep in the first post. It won't work for our older cherokees since we don't have digital odometers

Also, when testing on those yellow caps, be careful around the ECU RX TX ports. Remember... the diagram I posted is for 1988 cherokees, and Jeep sometimes changed pin positions, etc. between model years

.

-Nick

limbmkr · #19 (**permalink**) 08-12-2003, 09:01 PM

Okay I havent messed with it yet since there is no problems!! no use to do it unless Problems appears.

Thanks Nick!

jeeepers · #20 (**permalink**) 08-19-2003, 10:01 PM

I guess not all autozones carry the computer to check diagnostic codes. I took my 95 grandcherokee in to the closest autozone to me and they told me that there is a small gap in years where it requires some special kind of computer that they don't carry and other autozones don't either. So.....since my check engine light came on the same day I drove it out of the shop after an overhaul on my transmission I was a little ticked. I took it back and its still at the shop where its been a week now?! I think they're just being lazy! argh!