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Discussion Starter #1
The recently acquired ‘03 Vogue TD6 (145k miles) has been nothing but trouble-free joyful motoring (not) :mrgreen:

Backdrop/preamble:

Started out with an array of HDC/ABS related warning lights. Purchased the RSW scanner tool and resat the various of codes across most ECUs. It seemed most were trivial and likely attributable to voltage drop and/or the battery going bad (i.e. repeated disconnecting, jumping, charging, etc). I replaced the battery with a (provisional) 50Ah (small) battery and the car functioned like it should (free of any warning lights) for a couple of weeks.

Then the key remote stopped working, and about a week later the main battery suddenly was drained overnight (down to 5-6V). Upon charging the battery (while connected), a relay (?) started going frantic from inside the “E-box”. Disconnecting/reconnecting the battery solved this.

With the battery freshly charged (12.5V), the car now won’t start/crank. Tried a different battery as well as jumper leads from running vehicle (charging @ 13-14V) to no avail.

Both keys turn fine through all ignition positions, but there is no cranking action or click from starter relay/solenoid (nor that electric jerking sound from insufficient voltage or bad ground). Column lock disengages and all other power functions seem to work.

I have two sets of (fairly worn) keys, both work/turn in the door and ignition. One key (the least worn) have had working remote central locking, until recently. Checked battery condition in both remotes and voltage checked out fine (done within the 2 minute (?) window necessary to avoid resyncing). I guess there should not be any causality between central lock and ignition/immobilizer, as I understand the immobilizer transponder works independently from the central locking system and its battery? There are no codes stored on the immobilizer ECU.

Also, having attempted the resyncing procedure for the keys (dozens of times), all I get is ten flashes from the remote’s red LED. No confirmation from door locks. No information in display other than acknowledging11 the key when inserted (‘key in ignition lock’).

Checked all fuses (glove box and quarter panel) and tried to “wiggle” the shifter (i.e. back and forth between D, N and P) while attempting to crank in order to test neutral safety switch. Also tried pulling/reconnecting fuse #18.

Any advice is highly appreciated!
 

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Discussion Starter #2
I bought a new 110Ah/920CCA Varta that I wrangled in there with 12.7V across the terminals only to make zero difference. Also measured 0V (i.e. 0.4-0.7V) between ground and the + cable on the solenoid atop the starter when trying to crank.

Is there another starter relay (I see the V8s have one behing the battery)? Could the "lazy starting" system somehow be the culprit?
 

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2006-2009 Range Rover MkIII / L322
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Heres a description of the starting and power distribution circuits on a Td6, there is no starter relay at all in TD6 engine, it is all handled by the immobilization ECU itself.

Starting

The starting system on the vehicle comprises a 12 V starter motor which drives the engine to start the combustion process. The starter converts electrical energy into mechanical power. The vehicle electrical system must be capable of supplying sufficient power to enable the engine to be cranked. Range Rover features 'lazy starting'. This entails the driver not having to hold the ignition key in the 'crank position'. Starting of the engine is controlled automatically by the Engine Control Module (ECM), which provides power to the starter motor until engine speed is greater than 400 rpm.

Td6 Power Distribution

Feed from the positive battery terminal (C0192) is supplied to fusible link 2, fuse 18, and fuse 53 of the passenger compartment fuse box (C0632) on an R wire. Fuse 18 (C0584) provides a constant battery feed to the immobilisation ECU (C0059) and the steering column interlock ECU (C2055) on a pair of RY wires. Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099) on an R wire. When the ignition switch is turned to the 'auxiliary' position, current flows across the switch (C0099) to fuse 39 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 39 (C0587) provides an auxiliary ignition feed to the immobilisation ECU (C0059) and the steering column interlock ECU (C2055) on a pair of PB wires.

When the ignition switch is turned to the 'ignition' position, current flows across the switch (C0099) to fuse 31 of the passenger compartment fuse box (C0585) on a G wire. Fuse 31 (C0587) provides an ignition feed to the steering column interlock ECU (C2055) on a GB wire.

Fusible link 2 of the passenger compartment fuse box (C0591) provides a constant battery feed to the ignition switch (C0099) on an R wire. When the ignition switch is turned to the 'crank' position, current flows across the switch (C0099) to the immobilisation ECU (C0059) on a BY wire.

If the immobilisation ECU (C0059) has received a valid signal from both the transponder coil (C0049) and the steering column interlock ECU (C2055) when the ignition switch is turned to the 'crank' position, it transmits a rolling code to the Engine Control Module (ECM) (C0331) on a BP wire. The immobilisation ECU (C0059) also provides a feed to the starter motor relay (C0179) on a B wire.

 

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Discussion Starter #4
Thanks for the input, Mark. I thought I had responded some way back, but apparently my reply wasn't processed somehow.

The saga continues.

I thought I had found the culprit to be the starter solenoid, and I was able to start and use the car by shorting the two largest prongs on the relay with a screwdriver. This would work a week or so until the starter started not engaging the flywheel and spin freely. Naturally, I believed this to be the actual solenoid - which more or less was confirmed when I tested the solenoid directly on the bench with 12V and ground applied directly from a battery. The solenoid would not respond and sometimes jerk randomly.

Lo and behold, a new (2nd hand reman) starter/solenoid later I hook it up to the harness on the car (using a ground clamp instead of bolting it on the bellhousing), and I once again get zero action from the ignition key. Unhooking it and testing the solenoid on the bench it seems to respond like it should. Bolting it back on the car (this time all the way), and still no reaction from the key (nor click from relay).

When shorting the hot 12V from the battery to the small signal input on the solenoid (I get zero voltage read on this when just turning the key), the starter will engage the flywheel for a couple of revolutions until it somehow releases and the starter is left spinning freely. Also, I confirmed that there are 12+V going in on fuse 53 - which supposedly connects the ignition switch with the starter.

From RAVE: "When the immobilisation ECU (C0059) receives an ignition crank feed from the ignition switch (and all other starting parameters have been met) it provides a feed to the starter motor solenoid (C0179) on a B then BY wire (...)"

What is meant by "B then BY", "then" as in some sort of progression? I assumed that the B is ground (it's thicker) and the BY (in my case it's black + green) is the positive starting signal?

Any other ideas?
 

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They are the colors of the wires involved. B is Black, BY is black with yellow tracer.
 

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Yeah, I am aware of the color coding (although mine actually has a green tracer, so BG), I was referring more to the use of the word "then" to understand the flows of current. Should it just be read as "and"?

Anyway, I stumbled across some posts on another forum by an individual that had the same issue (no action with ignition in the 3rd position) - and he had found it to be the actual ignition switch, and cured it by cleaning up the inside of the switch. So, crossing fingers while tearing into the centre console, disassembling the bottom unit from the ignition switch, opening it up and cleaning up the points and tips with some 800 grit sandpaper and electro cleaner. I found that one of the tips in particular had a good amount of dust/gunk built up and believed for a minute I had located the culprit. But alas, problem still persists.
 

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This is the Gas Version:

RR_L322_Starter_Circuit_Diagram_2001.jpg
This is a 2001 Starter circuit (hope its bigger than the preview), the BG is a voltage signal to the Engine ECU that tells it the the starter solenoid is engaged. The B cable is the battery cable connected to the jump post on the firewall and running to the starter and it is always hot. The BY wire is the input wire from the immobilizer that actually pulls the starter solenoid in.

This is the TD6 version:

RR_L322_TD6_Starting_Circuit_Diagram_2001-2.jpg
 
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