OBD Connection

stl_TJ

Member
Original poster
Joined
Sep 30, 2020
Messages
36
Location
St. Louis
Went to get emission inspection this weekend, their reader wouldn't connect to get the status. Tried just a generic POS reader and it wouldn't connect either. The generic one was really a walmart special, it powered up so I know there is power & ground. Checked all the fuses behind glove box & pdc and all have continuity. Brought it home and tried to connet my elm & torque and got the same thing. ELM powers up and Torque see's it so again, there is power.

While searching I cam across this post, and there was a question if the Oil gauge was working. In that case it was, but in mine, it isn't. Figured this was just the sender that needed to be replaced but haven't got around to it (part is now on order).

Could a bad oil sender cause the OBD to not work? Seems weird.

Check engine light does light up during startup. I can even make it throw a code if while the key is in the on position I disconnect/reconnect the 3 connectors at the ecu.

This may or may not be related to the misfire issue I had last month. The oil sender stopped working once I replaced the bad coil wire on cyl 1.

If the oil sender couldnt cause this, what else should I check/test?
 
3 different scanners and none work. My scanner has always worked with this TJ so I know it isn't a scanner issue. it is what I used to see the misfires I was having a month ago.
 
3 different scanners and none work. My scanner has always worked with this TJ so I know it isn't a scanner issue. it is what I used to see the misfires I was having a month ago.
Funny thing was. The first scanner I used at one time DID work on my TJ. Not sure why it stopped working. I bought it years ago for this particular Jeep and used it for years until it stopped working. That's why it was so puzzling to me. It still does work for my son's Jeep but his is a 2003 and mine is a 1998. Different bus system.
 
Anyone have the powertrain service manual for the 99? I have one for an 02, but that is PCI bus not CCD.

I am almost positive the issue is with the pcm but would like to do any troubleshooting with the obd before ordering a replacement one from Mark. I know the reader I have and others I have tested will work perfectly fine with this TJ so it's either a wiring issue or a PCM issue. Just want to make sure I check wiring first cause that is cheaper then getting a PCM.

I have verified there is 12v & ground at the obd but I'm at a loss as to what else to test/check. Never had an issue with reading obd on any car so I'm at a loss what to do.

Thanks
 
Anyone have the powertrain service manual for the 99? I have one for an 02, but that is PCI bus not CCD.

I am almost positive the issue is with the pcm but would like to do any troubleshooting with the obd before ordering a replacement one from Mark. I know the reader I have and others I have tested will work perfectly fine with this TJ so it's either a wiring issue or a PCM issue. Just want to make sure I check wiring first cause that is cheaper then getting a PCM.

I have verified there is 12v & ground at the obd but I'm at a loss as to what else to test/check. Never had an issue with reading obd on any car so I'm at a loss what to do.

Thanks
The 99 FSM can be found here if that’s what you need:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
 
I have the FSM but it says to refer to the powertrain manual.
I wasn’t sure if it was different or not. I can only find hard copies for sale online. They aren’t expensive but an online version would be better. Sorry I wasn’t any help