I have a 1995 XJS 4.0. I have code P0413,an open circuit.

I have verified the following operate: air pump, egr, relays, and fuses.

The connect at the ecu appears to be fine. Power is present at the air pump and egr. So, I believe the open circuit is in the wire harness.

Near the harness connection, at the air pump, there is a diode contained in clear shrink plastic. The power supply wire (purple with yellow strip) soldered to the diode has power for the approxiate 30 seconds. The wire soldered to the other end of the diode is a solid black wire. When purple wire is energized, the black wire is not.

My theory is that the black wire should energize my tester when there is power present at the purple wire. But I'm not confident in my theory. I don't have a detailed wiring schematic to know where the black wire goes to. And I don't want to do a bi-pass test to see if my code goes away for fear of doing other possible electrical damage. Help

In the mean time I ordered some 3 amp diodes and a ohm tester.

 

Welcome to the forum Scott,

I've moved your question from General Tech Help to XJS forum. This is the place to post questions about your model.

I've also deleted all your other posts from X300 forum.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Is it this, what I had pictured in another post?

http://www.jaguarforums.com/forum/xj...arness-174659/

 

Yes VEE, That's the diode. I stripped the shrink wrap off of it. I've ordered an ohm tester so I can verify if this 3 amp diode is the culprit of my p0413 open circuit error for the secondary air pump.

I did try a temp bi-pass. The check engine light stayed off seconds longer, compared to before, until the air pump fuse blew.

 

VEE, thanks for referring me to that post. The wiring diagram is what I needed. I see the wires going to that diode and where they sourced from. Thank you so much.

 

You will need a IN4006 diode. You can order them from eBay, Amazon, etc.

I ordered a 5 pack, I can mail you one over... I'm only gonna use 1.

 

Thanks. I ordered a 5 pack yesterday on eBay as well. But thank you anyways.

 

Well, I'm disappointed to report that the diode wasn't bad. So, the error code keeps coming back. Within moments of the car starting. Strangely enough the car runs great. The air pump does it thing at start up. The check valve I'd fine. The wiring diagram doesn't show any interruptions. So now I'm at a loss. It might be time to drop it off at the shop. ��

 

I know you probably already know this, but I'll post anyways:

Code P0413 is tripped when the following occurs:
1. Air injection relay removed
2. Air injection relay (coil circuit) open circuit
3. ECM to air injection relay (coil) wiring open circuit
4. ECM to air injection relay (coil) wiring short circuit to B+ voltage