So found out that my ECM fuse block is cutting power to several fuse slots when hot.
Causing engine and transmission errors codes.
Doesn’t even try to start.
Looked up part LJB2800FA (original bad part) and found that part LJB2800CA is supposed to supersede the FA part.
Bought the CA part, but once it arrived noticed it has one less fuse slot and the underside pins for the harness connection are different.
The plug would fit, but pins are different.
I can only assume that the parts are not interchangeable.
Does anyone have any knowledge of this supposed interchangeability ?
Thanks in advance.

 

On with the nut on is my bad FA part, other is new CA part.
The 20A slot does not exist on CA, and the black harness connector pins are different.
Just checking to see if anyone know before I order another part. Took the CA part over a week to arrive.

 

Hi KV,
Heritage shows the replacement for the LJB2800FA is LJC2800CA not LJB2800CA.

I suspect that you may be OK to use the CA replacement you have, as that additional fuse circuit is for the intercooler pump on the supercharged motor, although I recommend some point-to-point checks to confirm.

There's at least one on the bay at the moment if you'd rather replace.

 

Thank You Greatly

 

You don't say what diagnosis you did that led you to a whole new fuse panel, but I just wondered if it may have only been the fault of the relay in that panel that supplies all the Engine Management Switched Power Supplies from that panel. That would throw a few faults if it went open circuit.

 

Replaced the relay with several (just in case I had a bad spare) and no difference. Put the original relay on a relay tester when circuit was failing to get power, and relay tested fine.
So trying the fuse box now.
Been chasing this problem for a year now.
Neither Dealership nor 2 highly recommended shops could figure out the problem.
Finally stumbled across the ECU fan, and noticed it also stopped working when hot.
Wiring schematic indicates that is is a simple circuit powered by the 5A fuse.
When testing fuse slots under failure condition, several were energized and several were not. After cooling off, failure condition was gone and all slots were energized. No other variables were introduced except allowing car to cool down. Since relay does not appear faulty, can only conclude it is the fuse block circuitry.
New fuse block (correct part this time) is coming tomorrow. If that fixes the issue, then will tear open old fuse block to look for defect. Never had this happen on any car before, so very curious as to what is failing in the fuse block.

 

Fascinating. Energized here means that there was no positive voltage on the high (feed) side?

If this is so, I'm curious, some of these fuses are fed by the battery power bus (2, 3, 4, 5, 8, 9, 15, 17, 18) and some by the engine management power bus (10, 12, 14, 16). Were the ones that were not energized only from one source (i.e. the battery or the engine management bus)?

 

Correct. No voltage on feed side.
Checked both sides, but only remember EMS side results.
Example: fuses 14 and 16 failed to energize, but fuse 15 had voltage. Other slots also failed to energize, but can’t remember which ones.
I do remember that the fuel pump did not come on either. Engine was dead silent (pun intended).
Sorry can’t give more examples, but once I noticed the issue, I did not write down which fuses. But I do remember the 3 fuses noted above.

 

Hit send too soon.
so it may very well be just the EMS circuit.
Very strange to have it cut out over heat though.
Waiting to find out if I have a bad solder on a diode.

 

Reason I was asking is that If it's all the feeds on the engine management power side, it comes from pin 5 on the relay (or the relay), down to 10, 12, 14, 16. Before the relay, it's the battery supplying power, just like the other side. So, if that is happening, and it is not the relay, it must be coming from that relay pin.

Yes, strange. Good luck with it.