I need the engine management/ECM electrical diagram to troubleshoot obd2 code p1229. Experiencing the limp mode, rpms less than 3000, rough idle. Thanks!

 

 

1999 Jaguar XJ8L 4.0L
vin#: SAJHX6047XC858788

 

Info for you.
Gus will have the Electrical Guide on his site.
jagrepair.com

 

Here's 1999 Electrical Guide.

 

Thanks for the info.

 

After testing the throttle body components, including voltages and ohming specs. the parameters are OK so I'm starting to consider that the ECM may be the problem. I would like to know if a used ECM is swapped in is it going to be a plug & play if the serial # matches exactly or are there additional steps required? Thanks!

 

Ok, wanting to check the TPS voltages before deciding on ECM as the issue. What is the procedure and the voltage specs for each wire on the 4 wire TPS connector? Also, if the voltages are not spec, what is the next procedure for checking the ECM? Thanks.

 

A replacement ECM (with the same VCATS suffix) will require an IMMOBILIZATION SETUP.(to introduce the module to the CAN bus)

 

Looks like there is a lot of info if you google "Jaguar x308 check voltages on TPS".

 

Thanks!

 

P1229 is throttle motor circuit current monitoring, it has nothing to do with the TPS.

is it driving on the limp lever? when the throttle motor is depowered you have to put your foot to the floor to get moving. bad motor can burn up the driver in the ecm, had to do a lexus a while back (same denso etcsi system).

 

Thanks. For that I'll need to see a technician with the appropriate scan tool and software- correct?

 

CORRECT
I use both WDS and IDS.
Working at the dealer and using these everyday back 20 years ago, I got used Ford units and installed new Hard Disk Drives. Jaguar software completes the kit so I have the same thing I did at the dealer.

 

Is the CAN bus on the ECM board or in a separate location?

 

also, I'm on my 4th used throttle body, with the car eventually going into what appears to be limp mode after throwing TB related codes and additionally P1000 and P1647, which is why I'm thinking the ECM is failing due to sporadic voltages to variuos TB components when tested with my multimeter. I'm a trained ET and HVAC tech, so I'm pretty good with a MM. Any thoughts on the ECM as the culprit?

 

M. Stojanovic posted the Electrical guide!
The network diagram is near the bottom of the document.(figure 19.1)

 

Got it, thanks.

 

If you haven’t already, I would check all the basics first like comparing battery voltage at the P/S front bulkhead connector and at the battery positive post to body ground, then across the battery posts to make sure the negative battery cable doesn’t get warm like it has high resistance. There shouldn’t be more than a .3 or .4 volt difference from the bulkhead to the battery. I would also check the ground cable underneath the engine to body. Next I would remove the “cool air box lid” for the under hood modules and take apart all those relays and check their contact points. You can be sure the A/C compressor and starter relay are the most worn out relays in that area. It’s really a good idea to visually check them all throughout the car when you remove the brown cover to make sure they’re all in proper working condition. If they aren’t too bad, you can use a small flathead screwdriver to clean them up. Another thing you could do is take apart that huge electrical connector on top of the transmission to make sure there’s no water intrusion inside or corrosion. Checking all the grounds associated with the engine management is also a good way to rule out any potential current or future problems.

 

this is how to diag an early denso electronic throttle circuit as used on aj27. follow closely