Hi, I have a really strange issue with my Daimler Double Six (1994/1995).

If I try and start the car too quickly after turning everything off, it won’t start, it doesn’t turn, nothing.

If I leave the car for a bit, it fires up as normal.

So just to flesh that out, if I park the car, turn it off, jump out to do something quickly, let’s say 60 seconds, then try and start the car, it won’t even try to turn over. If I leave it down a while, it will start as normal.

Any ideas?

 

The V12 starting system is almost the same as the inline 6 engine , the difference is the transmission on the V12 does not have a rotory switch mounted on the transmission

That being said this clears up some confusion on other read post on the X300 / X305 starter system

To split your starter system in half the starter solenoid relay must click closed every time by placing your finger on it

There will be other relays in the area that click at the same time, so you have to put your finger on it

The relay can click saying it has the correct command to close but it can have bad power contact points inside limiting the current to properly power the solenoid

You can swap this relay with a headlight , fog , A/C relay of the same part #

If the relay does not click you can still swap the relay

The relays come out easier with a shot of penetrating oil around the square mating half seams at the sockets , you have to unclip them and flip upside down

See page 17

X300 1996 LWB.pdf (jagrepair.com)

And page 54 and 54 only of this wiring guide for a like 96 ( the 95 does have some differences in other systems like exterior lights )

www.jagrepair.com/images/AutoRepairPhotos/jagxj1996.pdf

 

You have a chip in the key ?

 

I think so, it’s the original key (the car was first sold in Singapore).

 

I have to go to bed soon so let's go over some other things before I go skipping the key chip / exciter ring transponder component

 

The heart of the starter system is the Body Processor Module that has to get agreements or enables from things before it provides a ground to close the starter solenoid relay

The BPM is powered at all times and does not need a relay to close

The easiest thing to check is the ignition switch , the connector can get contaminated

The starter command in the form of a ground path ( agreement or enable ) to the BPM are pins 1 and 5 on the ignition switch

The pic is of the switch side of the connector half

Pin 5 is a car frame ground that the ground stud can get disturbed

Pin 1 to 5 is a spring loaded momentary contact so it can waiver on your meter and is not the most confidence building

 

Brilliant, thanks so much for the help, really appreciate it. There’s no hurry as well, I won’t have a chance to look at it again until the weekend.

 

The ignition switch does not not need to be removed , just the connector

The connector ( 5 wire ) is under the small curved cover under the steering column

The car side half of the connect lifts straight up to remove it from the mount to bring the work out to you

If it gets to it the switch removes from the key barrel, so no new key needed

The switch is not specific to the V12 and is the same part # as the X308 ( 1998 - 2003 V8 ) and X100 ( 2 door V8 )

 

G’day N Bath,

I had this problem with my V12 years ago and the problem was dodgy connections between the battery and the starter motor. The connections had all loosened. over the years and often there wasn’t enough current getting through to engage the starter solenoid and turn the starter.

Starting at the battery check both posts and the earth lead as well as the fuse box attached to the positive terminal. Next in line is a big connector and fuse box under the rear seat on the RHS, then the lead goes to the front footwell on the RHS with a brass connector through the firewall and on to the starter motor. All these various connectors tend to loosen over time and I cured my problem by cleaning and tightening all connectors. Before you launch into this check the alternator output at the alternator and then at the battery and if there is a voltage drop at the battery then you have a problem with the lead between it and the alternator.

Cheers and good luck,
Jeff Watson.

 

One way to test for this is to not have the car not running but the heater blowers running and compare the voltage difference at the battery and at the dedicated starter terminal post on the right front wheel fender well sheet metal

If the car is running the alternator feed will invalidate the test

If you remove the rear seat bottom pan from the car , protect the felt trim around the door from damage

Ask me how I know

Maybe put a old towel down

 

Thanks so much, I’ve got a much better understanding of the stater system, and can’t wait to give a few things a go. Hopefully this weekend.

Cheers.

 

Never reinstall the battery in backwards

Positive post goes in positive direction of travel ( fwd )

Ask me how I know

 

I also have to try and find a new power steering pressure switch, and there’s not exactly a lot of x305 spares lying about in New Zealand……. I’ve spent a lot of time searching.

 

On your V12 you have 2 extra relays as the ignition coil relay and fuel injection relay that must click closed , this strictly powers the ignition coils and injectors on the V12

This is other then the ignition positive relay in the right engine bay fuse box which also must also click closed to power the ECU as the 1st ECU power and some other things

The 2 previous mentioned relays are wired in and related to your power steering pressure switch, so they are related

This can be seen on page 59 right side

jagxj1996.pdf (jagrepair.com)

Ground stud PIG77right which is located ......

Pic on page 28 right side

This should be right by the relay other then the ground stud on the car frame boxed engine rail ( that one has about 4 wires on that rail ground )

From reading there have been problems with 1/2 your ignition coils with a faulty A or B bank coil module and a way to test would be if a good one warmed up by feel and a bad one stays cool

But someone would have other suggestions


Researching

 

Wow, thanks! I was only replacing (or trying to) the power steering pressure switch because it was leaking. I assumed all it did was flag to the ECU of the pressure was low or high, which threw up a check engine indication. There’s heaps of things for me to try. I’ll give it a good crack and see how I go!

 

The above post 2 relays will not keep you from the starter rotating the engine

So you can skip them but have in mind to clean the ground stud for future reliability

But you must have the right engine bay fuse box relay to click closed to power the ECU to provide a enable , different then ECU engine regulation

The Security Lock Control Module and Body Possessor Module are hot at all times as the 2 fuses in the truck bypasses the relay in the corner of the trunk fuse box

This would be the enable or agreement half ( which includes your ECU ) of your starter circuit , the other half being power or muscle

Did we go over the large connector above your fuel tank ?

The connector can come loose and prevent you from starter rotation, but caution must be taken to not break off the connector lock over pins

It should have a tie wrap on it securing it to the secured position

The problem with it is that it is a through bulkhead connector that has layers of sheet metal keeping it from fully clamping closed to make good pin contact

a couple of layers of sheet metal are cut out already to make a hole but may still be interfering with the connector clamping closed

This is where you can't force it too hard and break the lock pins

So you might leave this as the last thing you look at

You can look for the tie wrap and pass on going further if present

 

You want to swap the right engine bay fuse box relay ( ignition positive relay ) first before the starter solenoid relay

The starter solenoid relay has 12 volts " sitting " on the on the control half or pulling half of the relay from the 1st ignition positive relay and the BPM provides a ground to close the starter solenoid relay

This would be point 32 circle double hash

This can be seen on page 37 which is the same fuse for the 1st power to the ECU at section 04.4 . 04.5 . 04.6 , and 04.07 flag

.456and 7 are US federal standards version and Rest of World versions of the V12 ( emissions control )

 

Crash switch can be on the edge of tripping

Located on the right side just forward of the ECU and which is forward of the right front door hinge

It is a 3 wire connector with a black rubber reset bulb

Does not always reset and the 2 White wires can be jumpered with a paper clip

Pic is for a right hand steering version

 

OK, after an embarrassing episode where I got stuck at a petrol station and the Daimler wouldn’t start, this issue went up my priority list.

So I checked the bank of relays on the LHS of the engine bay.
I had a diagram showing the starter relay as 4th from the left, that relay didn’t click when the key was turned.
However the relay third from left (I’m holding it in the photo) did. Based on the colour of the wires, I think that’s the right one (please correct me if I’m wrong)



So my understanding is that if the relay is working, then it’s nothing to do with the BCM, but more likely the starter motor (or power to the starter motor).

I inspected the cables under the rubber hoods coming through the bulkhead, and the one on the far left of the car looked corroded, the other two were fine, I’m not sure if it is part of the starter motor circuit, but I’ll sort it out anyway.


Any tips are welcome.

 

Just checked the document linked earlier in the thread by Parker7, looks like the document I had was wrong, as the doc linked above shows the starter relay as third from left, which makes sense.