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OBDII PROBLEM

XBoBJ

XBoBJ

NAXJA Forum User
Location
Spencer MASS
I recently went to get my jeep inspected and it failed emissions due to the jeep not being able to be linked with the emissions computer at the shop. We tried it a bunch of times, maybe it wasnt pluged in? maybe it was loose in there? After all that nothing.... So i went home and i notice my #2 fuse was blown in the pannel(cigarette lighter) , i took it out put a 25 in, blew imediatly, then i threw in a 30, same thing. My cigarette lighter plug was jammed in there since i bought it. It passed inspection once before with it like this, so i took the dash apart and unplugged the cigarette lighter, i dont smoke so its useless to me. i put a 5 amp fuse in. It was all i had at the time and it didnt blow, so im going to put a 25 in and take it back. is the OBDII plug on the same circuit as the cigarette lighter? Would that fuse being blown cause my jeep to not be able to be linked with the shops computer? Jeep specs in my sig. TIA
 
i know before i couldnt pull codes from the OBDII neither, i dont want to keep bringing my jeep to the friend thats inspecting it and having it not pass and wasting his time.
 
K & L are bus lines.

The K line is the bi-directional line. It both transmits & receives to all on board nodes on the bus as well as any off-board nodes that are connected.

The L line is a uni-directional line. It is for off-board nodes & is transmit ONLY!

You can check these too, key on & check the voltage on K & L with respect to signal gnd (#5). In the Idle state, the logic should be high (12V). The K-Line might give you a funny number (7-8V maybe)...all that means is that there is traffic on the bus.
 
Goat said:
K & L are bus lines.

The K line is the bi-directional line. It both transmits & receives to all on board nodes on the bus as well as any off-board nodes that are connected.

The L line is a uni-directional line. It is for off-board nodes & is transmit ONLY!

You can check these too, key on & check the voltage on K & L with respect to signal gnd (#5). In the Idle state, the logic should be high (12V). The K-Line might give you a funny number (7-8V maybe)...all that means is that there is traffic on the bus.
Click to expand...


goat thanks a ton, probably one of the most helpful posts ive gotten here @ NAXJA, are you a mechanic or something?
 
is it possible that my battery not being grounded to the body that the obdII port would not work, i noticed the wire that goes from the battery terminal to the body has fallen off.
 
Cough up, what $50 now, for a hand held scanner from Actron at the local AA store. Or take it to AA and see if they can read it with their store scanner.
AFTER you fix that ground, ground cause some nasty gremlins in Jeeps.
 
XBoBJ said:
is it possible that my battery not being grounded to the body that the obdII port would not work, i noticed the wire that goes from the battery terminal to the body has fallen off.
Click to expand...

im having a hard time believing that the jeep would even start with the ground from the battery connected to the side of the block.

opps, just reread and you said from battery to body. i didnt think the xj had a battery to body ground, but a ground strap from head to firewall. i added a ground from the battery to body on my 1989, but didnt think the obdII had one either.

grounds can cause problems make sure the obdII connector have goood ground at #4 and #5. i would clean as many ground connections as you can find in the engine bay. check the ground strap condition from head to firewall and also make sure the ground to the side of the block is clean and the connection is tight.

did you test, with a meter, the pins of the obdII connector that goat posted?
 
Looks like fuse 19 under the hood should feed the data link with a Tan/black wire. You could try to trace voltage from the power distribution center (underhood fuse box) down to the socket.
 
Looks like fuse 17 to me...if fuse is good, it may be a poor connection at C100 (big connector near junction block) or wire from headlamp switch to data link connector.
 
Last edited:
okay i have no idea what pin is what but igot 1 pin with 2volts 1 with 4 and another with 12 i got one solid ground and i got 2 that makes the tester hesitate the beep isnt solid.
 
Well something changed from your earlier posts. Originally you had nothing on any of the pins. Now you are getting some readings. What changed? Did fixing the bad ground change things? Did you find a bad fuse? We need to know what you have done to make your test results change.
In any case...it sounds like it may be functioning somewhat now...so go test it at Autozone. Ask them to scan you Jeep....they will do it for free.
 
i fixed the battery gorund.... i went to get it tested and the scan tool that auto zone uses and any other scan tool shuts off......
 
Not to hijack, but I have this same problem on my 2000, so I am watching this closely since my CEL just came on. My cheapo scanner basically locks up when I scan the Jeep, works just fine with my 96 Dodge PU, and 05 Ford Escape.:dunno:

I need to try the above mentioned this weekend when I get a minute.
 
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