It’s been a while since anybody has had to mess with a front fuse box, but it appears some have been deeper into it than a myself.

I need some help/confirmation. I’ve been battling a “no crank/no start” issue for awhile. I might have found the first part of my problem. Most of the saga is listed in one of my posts.

When reading the front fuse panel with key in run, I found no power (only 1.3v) at fuse 2, 12,13,14. Relay R11 appears to be triggered by the ECM by grounding. These circuits without power would cause massive codes as they feed Throttle body, ECU, injectors, mafs.

Surprising I went out last week, and it fired right up, with no codes, no EPB issues, ran perfectly with both keys. Started multiple times with absolutely no issues ran perfectly. Went to fire it back up and check for codes, and now back to “DEAD”. This really started to look like a weak/aging relay.

Checked ECM connector, no water traces, perfectly clean contacts. I think I have ruled out ECM issues, as it can run perfectly. No point of going after the starting circuit until I solve the fuse box issue. But my concern is the fuse box first. Then, I’ll start beating the starter with a bar, that usually works on Jags and Land Rovers.

Pulled the box to start checking relays. My head is ready to explode after reading to many schematics. Could you confirm that I’m reading that circuit correctly and that I tested Relay R11correctly. I used my REAL power supply (powermax) for testing prior to removal and on the bench eliminating the common x350 battery issues.

12v pos supply to fuse box bus (large post)

EC19-2 to NEG

DMM between common NEG and checked for 12v at pins EC19-3, EC19-8, EC28-12, EC35-1.

Nothing.

This seems similar to the R12 issue others have had. But this relay circuit also has a diode in it from the ECM which concerns me. I have another front box on the way. And then rebuilding my current box with new relays.

If anyone could please confirm that I’m reading it right and that I’m not way off track.

1) Should I have 12v out of relay R11 to fuses 2,12,13,14 while in run/start?

2) Is R11 triggered by Ground?

3) Am I testing R11 correctly?

4) Can I Install a “temp fix” with additional relay similar to R12? If so, what source would I use to trigger the relay.

Sorry for such a long note, but I’m totally stuck on this one.

Thanks

Mark

2006 SV8

Using factory 2006 Electrical Guide schematics FIG 01.8, Page 57

 

Did you test the circuit to see if the diode was blown? DDM diode test +ve lead to EC8 -ve lead to EC19-2. Then reverse leads. Can use Ohms - one way will be high reading and other low if the diode is good.