The problem was sporadic last year but it’s now permanent. I took my 2001 xk8 to get it inspected but the mechanic couldn’t read the diagnostics. Tried different readers and several days to no avail.

I get power in the adapter but still won’t communicate. He also tried a direct communication line bypassing the old one. That didn’t work either.

his solution is to take out the dashboard, about 7-8 hours of labor, to see if he can find a short.

im reluctant to spend this money without being assured he can fix it.

any ideas?

thanks in advance

 

I would try a different inspection station....

 

You'd have bigger problems if there was a generic problem with the CAN bus (OBDII). If you aren't seeing the car complain bitterly, this suggests, to me, that the problem is actually a disconnect near or in the the OBDII connector itself or between the connector and the instrument cluster.

A picture of the connector is below. An ohmmeter connected between pins 6 and 14, should read 60 ohms. if it's infinite, there is likely a disconnect between that connector and the instrument panel. If that is what it is, it probably shouldn't take 7 hours to find/fix that. Is your technician familiar with these cars? It should take less than half an hour to get to the cluster and do a continuity check across the two lines. Then fixing it depends on what is wrong.

 

OBDII diagnostic for our cars is only available over ISO-9141. It is not available over CAN or SCP. See if you can have the tech "force" the ISO protocol. Maybe there is an issue with other pins, and the tool is getting stuck. Other option is to look up the pinout of the OBD connector (standard stuff) and disconnect all but power/ground and ISO pins.

If you feel like investigating yourself, get a cheap ELM327 device (eBay, Amazon) and see if you can read the diagnostic data yourself with a mobile app.

 

Jamgee, Don't know where Stony Brook is, sorry, but if in NC, wait 2 weeks and the car is 20 years old and only will need the safety inspection.

 

+1 on trying a different inspection station. Happened to me once and a second station had no issues.

 

Entertainingly, one of the local technicians told me that the OBDII diagnostics were generally available for this era models over the CAN bus (ISO-15765) too when I was trying to get an ELM reader working on CAN instead of ISO-9141 (It works, just need a prepended command. Note that the CAN requests have the same call and response features, just needed to be programmed into the inspector's diagnostic box).

If it's only ISO-9141 (pins 7 and 15), these lines are wired directly to the Engine Control Module. This might take 7 hours to track and fix behind the dash.

Bottom line, however, checking these lines takes seconds if you have a multimeter. From pin 7 to 15 should be about 76 kOhms on a resistance measurement taken with a multimeter. From pin 7 to pin 4 (or pin 5) should be about half of that. Same for pin 15 to pin 4. Infinite resistance on any of these or a short (very low resistance ~1-2 ohm) tells you which line is problematic, if any.

Like others, I'd try another inspection station too.

Good luck and let us know how it turned out.

 

The car has no issues, it runs great. I suspect the mechanic is not familiar with this car. I’ll take to another station.

thank you all

 

Take it to a Jag specialist.