Fuel pump or harness?

p m · Sep 10, 2016

2010 LR4 - died today in the middle of nowhere. Spit out codes P0232 and P025C - both related to fuel pump, and both kind of hint of a short in the fuel pump circuit.
The fuel pump 25A fuse is blown; replaced, blown again within a second of ignition-ON. The engine almost starts and dies immediately, which kind of leads me to believe that the pump is not entirely dead.

Any wisdom on field fixes? I can't even identify the fuel pump relay - even with some Topix info.
Can the harness be accessed from inside the truck (Disco/late RRC style)?

Thanks for any suggestions!

jymmiejamz · Sep 11, 2016

Probably a fuel pump, but a harness failure is also possible. The relay is before the fuse in the wiring diagram, and the fuse powers the fuel pump driver module which is behind the left rear C pillar lower trim. I've definitely seen the fuel pump burn up and cause the fuse to blow, but from what I remember, the fuse wouldn't blow right away. The fuel pump cannot be accessed from the top, but the tank is very easy to drop out of the car.

p m · Sep 11, 2016

jymmiejamz said:
Probably a fuel pump, but a harness failure is also possible. The relay is before the fuse in the wiring diagram, and the fuse powers the fuel pump driver module which is behind the left rear C pillar lower trim. I've definitely seen the fuel pump burn up and cause the fuse to blow, but from what I remember, the fuse wouldn't blow right away. The fuel pump cannot be accessed from the top, but the tank is very easy to drop out of the car.

Thank you Jimmy, my late night with Topix yielded circuit diagrams and component locations. No obvious chaffing on the harness to the fuel pump behind the heat shield, and not much hope for hot-wiring the fuel pump. The tank is 3/4 full, so doing that on the parking lot in Page is not entirely out of question, but highly undesirable. Time for a call to AAA.

p m · Sep 12, 2016

Just got an email from LR North Scottsdale saying the truck starts and runs just fine.
I left it with a known-blown 25A fuel pump fuse in the under-hood fuse block...

jymmiejamz · Sep 12, 2016

p m said:
Just got an email from LR North Scottsdale saying the truck starts and runs just fine.
I left it with a known-blown 25A fuel pump fuse in the under-hood fuse block...

Amazing. I would speak to the manager. You probably have some n00b working on it and all service advisors are idiots. I'm guessing they replaced the fuse and it started, which would lead me to believe you have a harness issues, and not a fuel pump issue.

jymmiejamz · Sep 12, 2016

I think I found the real issue, they have a Overland Adventure section of their website.

discostew · Sep 12, 2016

I've seen the fuel pump feed wire get shorted in the left rear door sill area. specially if you have kids that climb in and out thru that door. You could pull up that sill trim pretty easily and look yourself at that.

You won't have any luck just supplying a battery voltage to the pump. It gets a ground from a driver when the truck is running. But since its blowing the fuse it's gotta be that feed wire. Or the pump but that's less likely.

p m · Sep 12, 2016

discostew said:
I've seen the fuel pump feed wire get shorted in the left rear door sill area. specially if you have kids that climb in and out thru that door. You could pull up that sill trim pretty easily and look yourself at that.

Stew - I had a 70-lb dog climb into that door in and out gazillion times on this trip, so it is entirely possible.

Jimmy - they said they haven't replaced the fuse. Unless there are multiple shorts (one in the back to the ground, and one somewhere behind the fuse box), I can't see how this is possible.

jymmiejamz · Sep 12, 2016

p m said:
Jimmy - they said they haven't replaced the fuse. Unless there are multiple shorts (one in the back to the ground, and one somewhere behind the fuse box), I can't see how this is possible.

That's because the technician didn't tell the service advisor that he replaced the fuse and I'm also going to guess that the technician doesn't know that you already replaced the fuse once.

p m · Sep 12, 2016

jymmiejamz said:
That's because the technician didn't tell the service advisor that he replaced the fuse and I'm also going to guess that the technician doesn't know that you already replaced the fuse once.

The second part is confirmed, the first - denied (or vague about).

jhmover · Sep 12, 2016

Must be a huge dealer. 1357 used cars? Around here if they have 30-40 it's a lot.

p m · Sep 13, 2016

jhmover said:
Must be a huge dealer. 1357 used cars? Around here if they have 30-40 it's a lot.

It's a huge Penske group of auto dealers - including many other brands. Looks like most of these used cars are not Land Rovers.

p m · Sep 13, 2016

Looks like fuel pump driver. Note to self to keep a spare for future travels.

jymmiejamz · Sep 13, 2016

p m said:
Looks like fuel pump driver. Note to self to keep a spare for future travels.

I'm going to say that they are guessing and that isn't actually your problem.

p m · Sep 13, 2016

jymmiejamz said:
I'm going to say that they are guessing and that isn't actually your problem.

It should be relatively easy to test, shouldn't it? One way - by resistance of the pump winding, and by verifying there's no short from either drive wire to the ground. Another - power it up and measure current.
You may be right; I'll know tomorrow, hopefully. It would suck to have to drive to Scottsdale and have to wait another day or two.

jymmiejamz · Sep 13, 2016

p m said:
It should be relatively easy to test, shouldn't it? One way - by resistance of the pump winding, and by verifying there's no short from either drive wire to the ground. Another - power it up and measure current.
You may be right; I'll know tomorrow, hopefully. It would suck to have to drive to Scottsdale and have to wait another day or two.

Well it sounds like you have an intermittent short circuit, so checking for shorts to ground isn't going to do any good if the wire isn't currently shorted. I'm sure the tech is going based off of the fault codes and not doing any real diagnostic work. This is even more likely to be the case for an out of town customer. If you break down 4 hours away, its not coming back to the him. The other scenario is that he replaces the module and also fixes the short before you even get the car back. You should authorise an overnight road test so that it breaks down on them instead of you.

p m · Sep 14, 2016

This is a very likely scenario. How would they do an overnight road test? Somebody will be driving the truck around at night?

jymmiejamz · Sep 14, 2016

p m said:
This is a very likely scenario. How would they do an overnight road test? Somebody will be driving the truck around at night?

A manager, shop foreman, or service advisor would drive the vehicle home and then drive it back to work the next day. We do it all the time and have employees that live 2 hours away.

p m · Sep 14, 2016

Thanks, I'll ask them about it when I hear from them.

discostew · Sep 14, 2016

Jymmie is right about the driving trucks home. I live an hour away and get asked to drive shit all the time. But I won't usually drive anything with a tow bill stapled to the ticket. Unless I was pretty confident of the repair and the guy working on it. Doesn't surprise me some ass hole wouldn't say anything about putting a fuse in it to get it running, and like Jymmie said with your out of town address the guy probably really don't give a shit.

Fuel pump or harness?

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