crash data - cranks but won't start

lrovy

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Just acquired LR4 MY15 from auction - well father wanted to follow my bit of passion with LR MY10 overlanding - here we go.

Engine cranks but won't start. Since it is auction one it went straight to body shop, though to put the car in and out for the minor fixes (hood, fender touched and bumper) they ask to have the engine working. My bad it wasn't sent straight to LR specialist, but that seemed like best take at the time - I was wrong.

Driver's airbag is deployed, not replaced yet - maybe that's causing it? It came with dead battery, replaced now. The start/stop one is untouched but that one shouldn't cause issue, should it?

Did read in workshop manual about cycle to perform to start car, but that didn't help.
Got SDD connected and here's dump of faults:

B1193-00 RCM - Crash event storage - Full and locked

That is the most concerning one - it is resistant to faults clear.
On physical side, deployed airbag hasn't been dismounted yet, not sure if it's not blocking it. Wasn't sure what's the right order.

Other codes:
B0001-13 RCM - Driver's frontal stage 1 - deployment control
B0002-13 RCM - Driver's frontal stage 2 - deployment control

B1211-13 RCM Driver safety belt retractor pretensioner deployment control
B1212-13 RCM J_14229_DTC_B1212

U0001-82 CAV (no mileage specified), date from the past (whilst other are with current date) - High speed CAN communication bus.
Well - this is concerning, though status is with question mark above the.

And then less important ones (it got hit on the right side - which is weird then it shows "left")
B123A-15 BCM Front left turn signal
B1D64-87 HCM Left headlamp swivelling motor circuit.


Spoke with airbag specialist, they say - that to start engine RCM shouldn't need to be reset... but it's Land Rover, so who know.

Fuel pump can't be heard - so hard suspicion is that it's BCM not sending signal to start fuel pump, hence engine doesn't start...

How to troubleshoot it - well all I need is to be able to start engine for literally 2 mins to push it in/out of the body shop. LR specialist is pretty far, like 150miles and sending car on tow track back end forth doesn't sound like a good idea (pircey) as it will go there anyway, just later.

Thanks in advance!
 

jlglr4

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We have an inertia switch somewhere. It shuts off the fuel supply in a crash. Should be on the firewall passenger side - I haven’t actually laid eyes on it myself. To reset, I think you just push a button. I believe those RCM codes might be related, so you might need to clear the codes first (I’d make a record of all the codes, then clear them all).

If that doesn’t fix it, I guess I’d start with checking the fuses (if you haven‘t already). There is a fuse for the fuel pump. Then move on to looking for an electrical signal to the fuel pump when the ignition is turned on.
 

lrovy

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Fuses look good.
Are you sure about inertia switch? Double checking as all my research (and am no expert - just research done) says that there's no physical inertia switch on LR4 - or at least couldn't find it in workshop manual or standard manual. There is procedure listed around cycling the ignition.
 

jlglr4

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I am not sure about the inertia switch. There was some discussion on these forums about it a while ago, and I thought there was, but maybe not.

I’d still try clearing the codes and see if that changes anything - if you haven’t already. Could be they tied the same function (fuel supply shutdown) to that restraint control module that operates the airbags.
 

jlglr4

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There is also a relay in the engine junction box for the fuel pump. You could check that as well. If the relay is tripping when you turn on the ignition, then you should see 12v at the fuse. If you have 12v at the fuse and you’re not hearing the fuel pump, then the problem has to be down stream - the fuel pump itself.
 

lrovy

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Thanks! I've been looking at wiring diagram, but being tired after crazy week at day job, the two electrons didn't connect in my brain about the order of fuse and relay.
How at best is to check if relay gets signal to enable fuel pump or just use the fuse and assume if there's no power - then, at least theory confirmed - RCM (air bag module) is the cause. Did some additional reading and feeling, only unconfirmed feeling is that because of airbags deployment and crash status in RCM, it sends the CRASH signal on high speed bus and as such BCM or ECU says, nada, no fuel, we had crash...

Not sure about US, but in Europe, if am not mistaken, regulators' requirement is that car has to have an ability to move and shouldn't disable itself - this is for services to be able to do their job easier and rescue lives at the scene of accident.
 

jlglr4

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When you are back online, the manual does seem to mention an inertia switch in the diesel model (see attached). It also references restraint control module codes under these symptoms.

If this is a petrol model, the manual doesn’t seem to mention either an inertia switch or the restraint control module in connection with a no-start condition. But - as you pointed out - the configuration might vary depending on regional laws.

I’m not a mechanic, but I think this is how I would proceed:

If there is an inertia switch, I’d start there, obviously. Otherwise, I’d start with clearing the codes (at least the ones that will clear).

Then, make certain the fuel pump fuse is good.

Then test for 12 volts at the fuse with the ignition on. If you have voltage - seems the problem has to be in the fuel pump driver module or the fuel pump itself.

If no voltage, then test the relay. Lots of youtube videos on this - basically, pull the relay out, put 12 volts to the coil side of the relay (you should hear a ”click”), then test for continuity on the switch/power side of the relay. If you don’t have a battery or other DC 12v source to use, you can take it to an autoparts store and have them test it for free (at least in the US).

If the relay is good (or bad relay is replaced), then you have to check for a signal voltage at the relay. Plug it back into the car and have someone turn on the ignition while you listen at the relay - if it clicks, it’s working. The other thing you can do is test with a multimeter for voltage at the signal terminal with the ignition on.

If the relay is good and working, and still no 12v at the fuse, then you‘ve got a problem in the power circuit for the fuel pump: battery to relay, relay to fuse, fuse to fuel pump driver module, fuel pump driver module to fuel pump, fuel pump to ground.

If the relay tests okay, but is not working when the ignition is turned on, then you’ve got a problem in the signal circuit: central junction box (CJB)/body control module (BCM) to fuel pump relay to ground. Probably check the ground terminal on the fuel pump relay first. If that’s good, then figure out why you’re not getting a signal from the BCM to the relay. That’s the tough part. I think I’d get right on the box first - find the correct terminal and check for 12v to rule out the wiring between the CJB and the fuel pump relay. If you have 12v at the terminal on the CJB, then possibly an internal failure with the CJB.
 

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lrovy

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I owe you a beer, at least!

The car is LR4, US import :) It spent its life in Texas, till now. In Europe it was 99% sold Diesel and these PSA (Peugeot design in LR starting with 2.7, through 3.0 and latest SDV6 in post-lifts have all issues - engine breaks after ~100miles or more). It's design issue. For this and couple of other reasons I went with petrol one and best option was to do US import - same path father went.

So, all US (NAS) spec applies. I only have workshop manual for pre-lift so it doesn't include SCV6 (v6 petrol super charged - AJ126), though it is castrated v8 (AJ133) ;) so probably a lot of logic applies. It says:

If the Supplemental Restraint System (SRS) outputs a crash signal on the high speed Controller Area Network (CAN) bus,
the ECM de-energizes the fuel pump relay to prevent any further fuel being pumped to the engine.


Knowing this and that RCM (which is SRS) outputs
B1193-00 RCM - Crash event storage - Full and locked

I've strong feeling that am dealing with software safety lock of fuel pump.
Relays are pulled out to the table and funny - it doesn't have the usual relay description of control pins and "data/power" pins. Will get father to check if relay diagrams are on the side of them.

The authorities - I thought that similar might be in US, but it might be different obviously. Do you know how is it in US re post-accident car behavior if it is allowed to block itself from starting after initial fuel cut off?

Thanks for detailed steps! Really appreciate it!
 

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jlglr4

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Wow, great find. I see that now as well in my manual, and that sure sounds right to me too. I think you need to replace the airbag and maybe the supplemental restraint module just to clear the code. What a terrible system if that’s true.

I don’t know what the post-crash car behavior rules are here in the US. The old inertia switch that can be reset on site seems like a much better system.

If you want a manual that covers SCV6, follow the instructions in post #4 of this thread: https://landroverforums.com/forum/l...-harsh-smell-2014-lr4-scv6-108880/#post799284
 

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