Sitting here in the cinema waiting for a film to start. Had to leave the car, no start. It reacts when I turn the key as fan stops and so on, so it's drawing some current, but no sound from the starter at all. No click, no rotation. Had just driven 40 miles, so battery should be charged...

 

I tried in P and N, no difference

 

You should add your model year and engine to a signature so people can help you.

I believe it's a 1977 v12?

 

when my V12 wouldn't turn over starter i called roadside repair, i watched as he checked.

He noticed a voltage drop between engine and earth point on bulkhead. Connected supplementary lead from engine to said earth point and the engine started.

Worth checking.

 

Still no start, and the movie was crap. We are being picked up in an hour.
I'm thinking it might be lack charge, the headlights were dim when my daughter in law arrived in the car and stopped the engine. We then took over and couldn't start

car is 1977, engine is 1989 HE. I thought my signature would show when posting from my phone, but apparently not....

 

If charging the battery doesn't help.....

Go to the starter relay and find the white/red wire. If you have two white/red wires you'll want the one that's heavier gauge. Remove it from the relay, noting what post it gets reattached to. Now apply 12v to the wire. The starter should engage....which tells us you have a problem with the relay or a problem upstream of the relay.

If jumping the white/red wire does not engage the starter then you a downstream problem. Poor connection, poor ground, or faulty starter.

cheers
DD

 

Thanks Doug

Starter relay exposed and investigated. Function not yet understood though ! According to the ROM it's the one placed on a bracket by the fuse box above the (LHD) drivers knees, and it does click while turning the key, so I suppose it's right ?

Connecting the thick brown and white/pink (two of them connected on a double spade) wires gives a little spark and first time a small click from engine bay. No start. 12.7 Volt measured, so charging cannot be too bad.

Turning the key to acc or ign pulls the relay. Continuing to start releases the relay. Is that what it is expected to do ? It's not what I expected...

 

Haynes describes the starter as pre-engaged type. I suppose that is what this starter relay controls ? Pre-engaging the starter drive and then some other system must ensure that it's not engaged after engine had started... ?

 

Potential from ground at brake console to inlet manifold is 40 mV with ignition on.

Adding and additional earth wire reduced this potential to 3 mV. Still no difference in starting...

 

Starter rotates, if I short the two poles at the starter motor solenoid.

It seems there is no 12V coming to the solenoid coil. I tested this alone using test lamp and video on phone. I will involve wifee as key turning assistant, when she's home again and use my meter instead.

I'm happy to have a LHD car. The steering column must be a bit in the way on end cars...

 

Wife is back, no 12V comes to the solenoid coil.

I then tried the obvious: connecting the 12V at the solenoid to the solenoid coil, and the starter runs as it shall

The fault is therefore somewhere between starter and ignition key...

Next will be continuity check between starter relay and starter solenoid coil.

My starter relay is by the way an ordinary 4-pin Hella.
The relay pos 194 page 242 in Haynes is 5 pin, but mine has after all worked... ?

The four wires is connected this way:
Thick brown. To the contact set
Thick white/pink. Two of them connected to the other side of contact set
Thin black: to coil
Thin white/pink with a dark sleeve: to coil

The thick brown is 12V supply
One of the thin wires is off, when ignition is off. It then turns to 12V potential in Acc and Ign positions and back to zero when the starter motor should engage.
I simply don't get how that should work ?

 

So , being a 1977/1989 clone doesn't make things easier

The later diagrams has no ballast resistor connected to the starter relay, and 4 pins looks correct.
I have found the following:
Resistance in the WR wire from starter relay to starter solenoid is around 12 kOhm. That means it's toasted.
I tried to connect the WR wire at the starter relay with 12V directly from the battery. Still just a tiny spark and no start action, which makes sense with the high resistance in the wire.
The black wire from the relay should connect to the gearbox inhibitor switch. It doesn't, it is just ground all of the time, so the car must be able to start in any gear lever position.
The output from the ignition switch seems wrong. It tells the starter motor to run in Acc and Ign. I was not in the car driving the last miles before this failure. The driver was my young daughter in law, so maybe the starter motor has been activated continuously and thereby causing the WR wire to fry. I will ask her if she had weird noises during the drive.

 

The starter relay looks like this and should be in the engine bay

https://www.bpnorthwest.com/relay-st...Fc5bfgodTywL8w


I don't have any 1977 diagrams but white/pink wires generally feed/control ignition-switch accessories: wipers, radio, and the like

I don't have time at the moment to read and comment on your other postings and test results but nothing will make sense if you're checking the wrong relay...so verify that first

I (or someone else) will come back later

Cheers
DD

 

Thanks Doug

This is the relay I have found and refers to. Maybe it just feeds radio and other accessories?

Where approximately will the real starter relay be located in engine bay ?

 

Found it in the ROM a few pages before the other relay. Now I have something to do tomorrow as well...
Right hand rear corner of engine bay

 

My experience is with later XJSs. On those the starter relay is on the RH side of the engine bay, just aft of where the diagonal engine bay brace attaches to the RH engine bay wall

Cheers
DD

 

I had some "interesting' travails with the starter's on my lump. The GM starter is similar in architecture to the Jaguar unit. Solved.


But, I left an extra "test wire". It is connected at the small post on the solenoid, along with the one that is connected to the relay. Now, a "back up" means of cranking the engine as an emergency or for testing ala compression.


So, here:


1. Caveat. trans in Park. Apply 12v+ to the W/Y post on the relay. Healthy crank? If so, work back to the ignition switch. They do wear out. I know!!! Or merely a poor
W/Y wire.


2. Same Caveat. Jump 12v + to the W/R post at the relay. Healthy crank. No?


3. Same caveat. Jump 12v+ to the small post on the solenoid. Healthy crank. I suspect so.


So, here, I would rebuild the electric circuitry from the ignition switch on down. And dependent on the above, a better switch as well.


And, for safety, restore the N/S feature on the black/ground leg of the relay. OK for us experienced seniors, mebbe, not so for the young'uns.


Carl

 

22RA relay found and pulled of. No more time for tinkering today, but I look forward to tomorrow !

 

Hi Leo,


Don't know if the attached will help ('89 model year) but Fig 3.2 shows location of starter relay and some of the other wiring diagrams may help.


LeeP

 

Happy days

It helped a lot to check the correct relay. There were no ground in the black/green wire meaning that the gearbox inhibitor switch is failing. Or something else in that direction...
New, direct ground added, and engine starts. Now there's no inhibitor switch, so it can be started in gear, so it will of course need fixing asap

Thanks for all your help, especially Doug for guiding me to the correct relay... ��