Thank You So Much Guys! I Found the Problem

Into the 11th day. the passenger side, under the glove compartment, remove the panel, there are 3 black plastic boxes line up, the first left marked "4. Starter Solenoid" in green, the box slide out with some force, disconnect the wires from behind, open its plastic cover from behind, slide out the entire blue unit, see the Starter Relay on the biggest from the left, it fails to contact and starter-not-cranking when ignition key turn, used the screw driver to push down the contact the starter cranks up even without turning the ignition key but engine won't fire up, so turn the ignition key with screw driver force starter relay contact, engine fires up immediately. Repeat it several times, and it is confirmed ! bad relay contact leads to intermittent non-starting issue. I am going to find myself a new unit but this box has 4 relays controlling also Door Luck and Window Heater,
Any advise on how to repair the Starter Solenoid? (Relay)?

See detailed photo : http://www.flickr.com/photos/10335277@N07/4913634564/

 

I woke up this morning, thinking, I might not identify the exact cause yet.

If the starter relay inside the multi-relay-box DBC1008 is not triggered when ignition key turn, it could be the electric current was not feed into the relay.
I could crank up the starter just by pushing the relay contact without turn the ignition key. I could crank the starter as well by jump across the brown(in) and white(out to starter) wires without ignition key.

So the problem is somewhere else, that prohibit the electric current pass through the starter-relay when ignition key turn.

I also checked the black wire (-ve), it works just fine.

Now I installed a temporary switch (jump across brown and white wires), when the ignition key fail to crank the starter, I will push down the switch for 1 second with key turn, then starter roars up, engine runs smooth.

But it is kind of silly. Can anyone advise other possible cause of that electric current not feeding into the Starter Relay?
Thanks
see photo link:https://www.jaguarforums.com/forum/a...pictureid=4759

 

I don't have a diagram to hand but should be a fairly easy task to trace the wire back with one and see what other wonderful "features" are in place that could prevent the power reaching the relay.

At least for now you can drive her

 

How's about a faulty ignition switch?

 

Thanks, in2,
I have been enjoying driving it after days of frustrating works.
And after I installed a switch (from my old lamp) by pass the Starter Relay, I am almost 99% certain that if the key fail to crank up starter, I can flip the switch to activate the starter. Investigation will continue few days later. Cheers

 

Thanks, Translator,

Honestly, after I installed an "emergency switch" to bypass starter relay in case the key fail to crank up the starter, Jag has been performing flawlessly without hesitation in the past 2 days, starter cranked up with engine fire up every time key turn. (I haven't use that emergency switch yet, touch wood!),
Surprisingly, my clock light also lit up it has been dead for years.

It is always this "intermittent" non-starting very frustrating.

I did thought about the ignition switch, but if turn-key can activate fuel pump, electric window, stereo, all the lights, fuel injection unit,
Can I assume the ignition switch is OK.....but something or some feature inhibit the "signal" of engagement to starter-relay. My strong suspicious is still the park/neutral sensor or the starter-relay itself isn't working. I will have to do some testing this weekend.

Cheers.

 

No, because the start the engine pulse is after the position 3 on the switch.

If you think about it you will see what I mean.

You turn the switch all the way to position 3 and then give it an extra twist against a spring return.

The car cranks, and fires and then when you release the switch it returns to position 3, with your pump, windows etc all working.

It would be worth looking at because you say that your temp switch allows you to start and run the car as normal.

 

Oh, Yes, Richard, Indeed. I saw the logic,

I forgot "after the position 3" is where the cranking of starter.

I will need to do some more testing on the ignition switch at different position.

Thanks a Lot Again.

 

Hi. Here it is 2018 and I find myself in the same predicament. 1993 Jaguar XJ6 4.0, only 39K actual miles, really good condition. Always starts in the garage, the fist time of the day, once per month or more often it will not start later in the day, usually when the engine and car are warmed up, although doesn't matter the season.

Condition is same as Mr. Chang, lights, internal fans, radio, windows all work (which is good when the car won't start and it's 95 degrees F outside). Turn key to START position, all appropriate lights/indicators come on, but no sound, no engine rotation. Several tries, wiggling the shifter from Park to N and back, no help. Getting out of the car and walking around, opening and closing the bonnet, usually just a matter of waiting it out.

When the car finally responds to the key, it starts normally as any other time.

I have used Mr. Chang's suggestion the last time this happened and manually pushed the Starter Relay contact arm on the Starter Solenoid relay inside DBC 10008 while the key was in the Run position; Engine started without any hesitation.

Has anyone found the cause and a resolution to this? Resoldering the PCB inside the relay box?

Thanks!

Rick

 

Hi Rick,

Welcome to the Jaguar Forums! It's great to have you with us.

Bad solder joints in those relay modules is a well-known issue with the XJ40. The relay module just clips onto and off of the mounting rail, so it's easy to remove from the car. Open the plastic case to slide the circuit board out and inspect it carefully for cold, starved or cracked solder joints - typically you'll find them around the relay pins. Reflowing the solder and adding more solder where needed will usually restore proper operation.

Please keep us informed.

Also, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don