I had a blown 5A fuse #4 behind rear, left hand heel board. Manual lists fuse as for “Diagnostic Connector.” I replace fuse & test with OBD-2 & get the expected P1111 system pass. I will redo the emissions next week.

A week b4 emission test I hooked up my Innova OBD2 3130. Normally it gives a yellow light & code P1111 to indicate System Pass. I last used a couple months ago a friend’s Honda CRV to read & erase a CEL code. This time, I got a reading BEFORE I turned on the ignition! 4 of 7 monitors were flashing & message said “No stored DTC codes.” It did not change when I turned on ignition. I checked to see if replace battery indicator was on, no. But, I replaced the batteries anyway. The Innova did NOT go to the set language menu as the manual says it does after battery replacement. It still gave the same strange reading even though it is not connected to a vehicle. 4 of 7 monitors were flashing & message said “No stored DTC codes.” I think this is some aberrant display & not at all a reading of my XJ8. I am thinking the Innova is broken. I manually went into Menu mode & reselected the English language. Turned off & then on & now it no longer displayed that strange message with some monitors flashing. It correctly displayed the “to Link, turn on ignition & press the Link button.”

I turned it off connected to my car, got the “to Link, turn on ignition & press the Link button.” I turned on the ignition & pressed the Link button & it powered off! If Press link again it again says: “to Link, turn on ignition & press the Link button.” When I do, it powers off.

I email Innova for support 5-23-2013, as of 5-31-2013 no reply.

So, I go to emissions & fail. I now go & check that friend’s Honda CRV & the Innova works perfectly. I’m now sure it’s my Jag that is the problem & it will be expensive. I had read about needing to replace Engine Control Modules for $6,000. So, I check the fuse lists & note every one that could be related & Eureka, it was the most likely one fuse #4 behind rear, left hand heel board. That was not the 1st I checked since I have much trouble removing the heel board. I don’t know a good way to remove that damn plastic clip that holds the carpeted cover in place. It has no slot & I end up grabbing it with a pliers & twisting & pulling further deforming it every time.

So, Why did my fuse blow?

 

Passed emissions today. Still don't know why that fuse blew.

 

I'd suspect a short in the Innova lead - have a look at the pinouts and test with a meter while waggling the lead.