Title should be edited to:
Emergency starter test and starter relay fix


If your starter relay is going fail, it probably wont happen at a convenient time and place. If it dies for good you may be stranded, if it is an intermittent problem by the time you get it to the shop or your garage for testing, the problem will likely be temporally gone. When it does happen you may have few tools and no test equipment with you. The following info can help you get home, or spot a troublesome bug before it goes back into hiding using only the parts that are in every XJ6 III (and others).

If/when the day comes that you turn the key to start but the starter doesn't engage, first make sure the car is out of gear. Get this wrong and you may be watching it drive itself into the nearest solid object (ask me how I know).

Follow the positive battery cable from the battery to the positive junction post on the firewall and look for the relay bank at the top of the firewall. The starter relay is the large one at the end with 5 terminals. Locate the heavy white/red wire and make a note of which terminal it is connected to and also the other terminal at the same end of the relay.

Disconnect the white/red wire and touch it to any piece of bare metal on the positive junction post. If the plastic connector at the end of the wire interferes with making a good connection, use a paperclip or other piece of metal to get the juice from the post into the connector. Does the starter engage and turn the engine strongly? If no, that means that the battery, cable, connections, solenoid or starter are the problem, not the relay.

If yes, good. Now cross your fingers and hope that the problem is a corroded contact in the relay. Take the white/red wire and connect it to the OTHER terminal. (you took note of it right?) there are 2 connectors on the terminal so there is room for it even if there is a ballast resistor bypass wire connected there. It wont mind sharing the terminal a bit. Both terminals are electrically identical and the other one is likely in better shape as it hasn't been passing solenoid size current all its life.

If the relay will start the car now it would probably continue to do so as is for years, but curiosity would have me opening the can to see what is going on inside and then I would dress the contacts with a thin file (don't use sandpaper or a stone). If you want the reliability of your ride to go up rather than down, it is now a good candidate for replacement.

If hot wiring solenoid got the starter turning but swapping the terminals didn't work you may still be able to get the car home under its own power. Double check to make sure the the trans sill is/really is out of gear and then turn the ignition on. Now hot wire the solenoid again and see if you can get the car started.

With luck you are headed home at this point. If hot wiring the solinoid didn't get things cranking good, lets hope your trunk has jumper cables, tools and a hard copy of this:
Engine Will Not Crank Checklist (Thanks Doug)

-Paul

 

thank you Paul for the info

 

There is some related info on swapping out the starter relay for a generic unit here Jaguar Specialties.

This will be my next bit of preventative maintenance I think.

Cheers

 

The Bosch 0332204150 mentioned should work fine, but you will be replacing a double pole/single throw relay with a single pole/double throw. Be sure to ignore pin 87a. If you want to retain your ballast resistor bypass, use a y connector, piggyback terminal or similar to hook the white/blue wire to pin 87 along with the wire to the solenoid. -Paul

 

Just resurrecting this useful thread:

Can anyone confirm which terminal on the generic Bosch relay the White/Yellow EFI diode pack wire should be connected to? e.g. should it be piggy-backed with the W/Y ignition switch wire on terminal 86?

Cheers,

 

The terminal designations on a generic 'Bosch style' relay would be 85-86-87-30

85 black or black/green (same as terminal W1 on original relay)
86 white/yellow (same as W2)
87 white/red (same as C4, C1)
30 solid brown (same as C2)

It should be noted that the Series III XJ6s *with a 4.2 engine* did not use a 'resistor bypass' as mentioned above....so don't bother looking for one

Cheers
DD

 

Thanks Doug. Actually my relay does have a white/blue wire connected, so goodness knows where that goes to if there's no ballast resistor bypass. I'm ok with that one anyway if it can be piggy backed to 87.

I'm just still a little unclear about how to connect the white /yellow which goes to the EFI. I can only think it must piggy back onto 86 (W2)...

 

In my diagrams it shows 'not used' for the white blue wire. It probably disappears into the harness somewhere.

Seems that some cars had the white/blue wire, even if left unused, and others did not. I'm sure we'd find a pattern if we looked closely enough at a large sampling


It can be



Yes, piggy back onto 86

Cheers
DD

 

I've mostly been going by the S57 (fig.2.1) diagram which doesn't mention the BW wire, I only picked up info. on that wire in this thread. Mine probably isn't connected to anything at the other end either, but it is currently connected to the relay so I've been loath to ignore it. Anyhow, thank you for your guidance, I think I'm clear enough to do the swap now!

Cheers,

 

My offline chat with Tony (Jagent) and looking at my post in this thread talking about this as an intended preventative maintenance job in Dec 2014 finally shamed me into action.

Its a simple update and far better than waiting for the start relay to mess you around some rainy night. Took about 30 minutes, don't even have to think about mounting with the relay tabs already in the right place. Bit quicker for me as I don't need the extra wire for my non existent FI.

Before





During




After

 

Hi Steve, I bought a Narva 5 pin, rated 24v 30amp (normally open) at Autobarn. Is yours 4 or 5 pin? I couldn't find a 40 amp 5 pin, although I think a 4 pin would do the job given that the 5th terminal 87a is redundant. Hopefully I haven't got the wrong relay!!

Got distracted and haven't put it on yet, although I have set up some new connectors to piggy-back the WY EFI wire and the WU ballast resistor bypass wire (yep, I'm still going to connect that one since it's on there already! I notice it is also connected to the coil - assuming it's the same WU wire).

EDIT: Just spotted the 12v 40amp on ebay...

Cheers,

 

That one is 5 pin but isnt needed for that role. That particular relay just ties the two output pins together.

Its the most straight forward application of a relay so you could probably adapt almost anything with a decent current rating. Why did you go 24V, just out of curiosity.

 

TBH mate, I didn't notice the 24v until I got it home!