Hello All,
I am new to the forum, but have read quite a few posts relating to this issue. I recently acquired an 01 XJ8 4.0L with some front end damage from my step-father. I replaced the damaged body panels...grill, hood, fenders etc. The couple times I drove it while performing the body work the engine failsafe mode light was on but it seemed to drive fine. My plan was to go ahead and have it inspected, liscensed, insured, etc. then address the warning light issue, then some matching paint for the front clip. The day I was taking it to get inspected it went into limp mode and more lights came on, they were failsafe engine mode, transmission fault, trac not avail, asc not avail I took it to the parts store and they pulled codes P0102, P0112, P1111, P1121, P1222.
Since then I have cleaned the MAF sensor and connection and cleaned the connections on the throttle body. I have also purchased a bluetooth OBDII reader. I have done several resets and when I do I am able to clear the lights and the one code that keeps coming up consistantly P1121 but keep getting the same results...limp mode with failsafe mode, transmission fault, trac and asc not avail and of course the P1121. Sometimes it happens right away upon starting it and sometimes not until I get it up to speed, maybe third gear.
I am considering sending the TB to be remanufactured but I was hoping to get some input on what else I might try first and also some opinions of weather I am jumping the gun on the TB rebuild.
Also my stepdad said this happened before and he took it to a mechanic who cleaned some sensors and the problem went away for a while, he is not mechanically inclined and could not give me any more info...which sensors etc. Also he had a prospective buyer before the front end damage who supposedly took it to a mechanic who told him there was definately nothing wrong with the transmission...for whatever that is worth.
Any and all input would be greatly appreciated, thanks in advance.

Bruce.

 

You should charge the battery, and while doing that disconnect the neg. terminal. Getting the battery load tested is a good idea.

Then clean the plugs to the throttle body with electronic cleaner and locate the battery and ground connections to the engine and frame and clean them. Make sure you get the one from the bell housing to the frame.

After the battery is charged see if it holds about 12.6V overnight, otherwise replace. Then see what codes appear and come back here.

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Thanks for your reply RJ237. I cleaned the 4 connectors on TB again and I took a look at the ground strap from battery to frame and from frame to bell housing they both looked very clean and were securely tightened down. Are you suggesting I disconnect them and clean the terminal and frame then reconnect them? Are there other connections I should be looking at? Thanks.

 

These cars need a good, strong battery to operate properly. A poor battery will make all sorts of strange things happen, I had a low battery once and pressing the driver's window button opened the back window. The batteries also have a habit of going flat at any given moment if they are in poor health, so it's best to get a good battery like Bosch, Varta or Exide.

 

The various electrical connections can be tight but still have corrosion, so yes, you should take apart and clean.

 

Okay I finally finished with the initial work that was suggested. I disconnected and cleaned the both battery terminals at the battery and at frame also at the circuit breaker. Also the 2 other ground connections in trunk, the 2 in the engine compartment and the one at the bellhousing to frame. I then charged the battery (quite new ACDelco pro series 93 silver). It held 13.3v at full charge and was still at 13.1v this morning. I reconnected the battery cleared the old codes, started the vehicle and let it idle for about 10 min and checked the codes again...only P1000 came up. I then took it for a drive around the neighborhood. It ran great at first but not for long. First the Failsafe light came on then shortly after the limp mode, trans fault, trac N/A etc...basically the same thing as before. After I limped it back to the driveway I checked the codes and got P1000 and P1121. Any recommendations of what to try next is welcome.
Also I forgot to mention before that the reason it failed inspection was because it needs a new outer tie rod end on the passenger side. Also the sounder is still disconnected.
Thanks in advance for your continued help.
Bruce.

 

I decided to go ahead and purchase a new throttle body from ASI and installed it today. It seems to have corrected most of the problems. I still get the failsafe engine mode light after driving for a period of time but no other lights and the only code that comes up is P1000. It does not go into limp mode or give me the trans fault, trac N/A or check engine light and the failsafe light goes off when I shut it off and restart. I still have not done the outer tie rod...that will be tomorrow evening. Any thoughts on the failsafe light?
Thanks,
Bruce.

 

Shouldn't have it and the P1000 should have changed to P1111 so go hunting for what's still wrong.