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Discussion Starter #1
I was playing around with the jeep today and I decided i wanted to get the scanner out and get a couple freeze frames to see what the computer said what my idiot cluster doesnt.

Long story short, the scanner wont pull up codes or anything for that matter. I checked the obvious stuff- and threw the scanner onto my fiances escape.....reads fine. I then stopped at advance auto and they couldnt pull up codes either.

Is there a fuse or something to check as to why the information isnt being sent to the plug under the dash?

Thanks guys any help would be greatly appreciated
 

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did you turn the key to the 2nd position after plugging the reader in? and some models have an e-brake sensor for whatever reason, meaning it won't show without the brake set.

if that doesn't work :dunno:
 

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Yeah- both with engine running and off but ignition set to the "on" posotion.

Stumped on this one.
 

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bump.......anybody?

I've checked most of the grounds in the engine bay and I can't honestly think that there would be any problems with there because it's running really well.
The only thing I can think of is that there is a short to the plug under the dash?

Not sure where to start on this one.
 

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Irwin, I've come across this in other vehicles that had OBDI and OBDII. Look in the connector and make sure you don't have a pin that is bent and not making contact. You could also have lost the connection on the back of the OBD plug too. From what I've read around, a bad CPS will actually stop the OBDII from working. Good luck.
 

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I was playing around with the jeep today and I decided i wanted to get the scanner out and get a couple freeze frames to see what the computer said what my idiot cluster doesnt.

Long story short, the scanner wont pull up codes or anything for that matter. I checked the obvious stuff- and threw the scanner onto my fiances escape.....reads fine. I then stopped at advance auto and they couldnt pull up codes either.

Is there a fuse or something to check as to why the information isnt being sent to the plug under the dash?

Thanks guys any help would be greatly appreciated
If it will help here's an image of the data link connector. The connector is shown upside-down but I think you can figure it out.

Pin 16 is power for the scanner. It comes from fuse F17 in the PDC (Battery voltage). Use your voltmeter to read from pin 16 to a good ground near the connector. If batt voltage is read - okay. Next, go from pin 16 to pin 4 (ground for the scanner) If batt voltage is read - okay. Repeat using pin 5 as ground. Note that both pins 4 and 5 use the same ground point so the ground pins are redundant. Note that fuse F17 in the PDC also feeds the headlamp switch. You had two shots at trying to read voltage at pin 16, if you have headlamps but no voltage at pin 16, there's an open bewteen the data link connector and fuse F17.

Pin 3, CCD Bus (+) and pin 11, CCD Bus (-) are fed from the PCM. If you put your voltmeter positive lead to pin 3 and your negative lead to a good ground near the data link connector you should read around 2.4 - 2.5 volts, and reading from pin 11 to a good ground you should read the same as at pin 3. You may see a slight variation.

 

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Discussion Starter #7
Awesome information from a fellow michigan jeeper.

I will be checking this out tomorrow morning after I get out of work
 

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As a note: I bought a Actron CP9180 scanner about a year and a half ago and when I first plugged it in it would not work....nothing. I checked the pins on the data link connector and found pin 16 corroded. I cleaned up pin 16 and then it worked.

Something to check out first.

Typical XJ....corroded pins, grounds, etc.

Michigan: The hub of all knowledge. :cheers:
 

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OBDII Connection Issue

If it will help here's an image of the data link connector. The connector is shown upside-down but I think you can figure it out.

Pin 16 is power for the scanner. It comes from fuse F17 in the PDC (Battery voltage). Use your voltmeter to read from pin 16 to a good ground near the connector. If batt voltage is read - okay. Next, go from pin 16 to pin 4 (ground for the scanner) If batt voltage is read - okay. Repeat using pin 5 as ground. Note that both pins 4 and 5 use the same ground point so the ground pins are redundant. Note that fuse F17 in the PDC also feeds the headlamp switch. You had two shots at trying to read voltage at pin 16, if you have headlamps but no voltage at pin 16, there's an open bewteen the data link connector and fuse F17.

Pin 3, CCD Bus (+) and pin 11, CCD Bus (-) are fed from the PCM. If you put your voltmeter positive lead to pin 3 and your negative lead to a good ground near the data link connector you should read around 2.4 - 2.5 volts, and reading from pin 11 to a good ground you should read the same as at pin 3. You may see a slight variation.

Thank you for this info. I had OBDII connection issues as well. The 2 ground pins were open. I ran a wire from the chassis to pin 4 and the scanner worked, which allowed me to pull the codes and resolve my TPS issue. I had no idea what the trouble was. Thanks again for the post!:thumbsup:
 

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Thank you for this info. I had OBDII connection issues as well. The 2 ground pins were open. I ran a wire from the chassis to pin 4 and the scanner worked, which allowed me to pull the codes and resolve my TPS issue. I had no idea what the trouble was. Thanks again for the post!:thumbsup:
You should check the two grounds (4&5) in the engine bay. Both wires terminate in one ring terminal attached to the engine block at the oil dipstick tube bracket attach stud. It's called G102.

 

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You should check the two grounds (4&5) in the engine bay. Both wires terminate in one ring terminal attached to the engine block at the oil dipstick tube bracket attach stud. It's called G102.

Thanks CCKEN,
That is probabaly the cause of my OBDII trouble. Having just rebuilt the engine I probably missed the connection
 

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I'm unable to scan for codes on my son's 1996 Cherokee 4.0l. Following this thread I checked and have 12v at pin 16 and both pins 4 and 5 are good grounds. What I don't have is any voltage at pins 3 and 11. We just rebuilt the engine and it runs fine except for idling. Sometimes it idles at 700 rpm, other times at 1200. I've replaced the IAC solenoid twice and it hasn't solved the issue. Could it be that the ECU is faulty and causing the issue. The Jeep sat in the driveway for a year before we had the chance to do the rebuild. Thoughts?
 

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Are your gauges working normal? Also, try unplugging the Cam position sensor (under the dizzy). Mine caused a no start but a telltale sign was a lost of OBD connection and the dash lights were wonky.
 
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