My 84 XJS sometimes won’t start when you turn the key. This usually happens after driving it and then stopping briefly. It usually always works when cold. I’ve discovered that when it happens if I then turn the ignition off an back on without engaging the starter and wait for about 5-10 seconds before running the starter it will usually work. Any idea if this sounds like a problem with the starter relay?
2nd question. when I looked at the starter relay I notice next to it was an empty relay socket. Looking in the parts manual it says it is a start injector relay. Any idea why that would be missing? I though these were the standard 5 pin relays you can buy at autozone but when I tried replacing the feedback inhibitor (next to the start injector with one from autozone it wouldn’t start and then looking at the bottom I see that 2 pins are reversed from the autozone version. So I pulled the pins from the pigtail and reversed them and now it works with the new relay. Does the missing start injector relay have the same pinout? i.e. can I use the original feedback inhibitor relay in the missing start injector position? They have a different part number in the parts manual. AGU1068 for the start injector and AGU1097 for the feedback inhibitor.
Possibly, yes.
Or a poor connection, or faulty ignition switch, or…
Do you have a 12v test light or meter? You could do some simple tests next time the failure occurs
Jaguar stopped installing the cold start injectors circa 1983-84…but may well have left the wiring in place. And, even on cars that originally had 'em some owners disable the circuit.
Some are, some not.
In some cases Jaguar used relays with an internal diode, often identified by a diagonal paint stripe. But,if the stripe is gone, the diode will be seen in the miniature schematic on the relay itself.
Jaguar was also fond of “Dual 87” relays. Rather the the common 30-85-86-87-87A terminals these have a different function, with terminals marked 30-85-86-87-87. Again, this can been seen on the relays themselves.
Cheers
DD
Thanks, yes the original relay has a diode. Not sure of it’s purpose other than to short out if you were to reverse polarity. No current would flow through it in a normal installation. Unless it’s a zener diode for preventing over voltage. Can you point me to a pinout diagram of the starter relay? It doesn’t have the standard 30-85-86 etc. labeling so I’m not sure what pins are supposed to be energized when you turn the switch. They’re kind of pricey for a relay as well.
https://www.ebay.com/itm/Lucas-starter-relay-SRB301-C36611-22RA-Triumph-TR6-Jaguar-E-type-XJ6-XJ12-XJS/123073638912
I saw this post
http://www.jaguarspecialties.com/tech_tips10.asp
and thought I could try it but I think the original relay has more than 5 wires on it so It confuses me.
The S57 wiring guide is useful here. Worth having !
Anyhow…
C2 Solid brown wire, constant B+ voltage
C1 heavy white/red wire to starter, thin white/red wire to fuel injection ECU
C4 white/blue. Might not even have that wire. If you do, it might be unused
(C4 and C1) are joined together inside the relay, by the way)
W2 white/yellow from ignition switch, 12v+ with key turned to ‘start’
You might have a white/blue wire here as well, to the 45 second timer
W1 ground in “P” or “N”, probably white/black from the inhibit relay (which is triggered by the neutral safety switch)…but I’m not sure if an '84 has the inhibit relay
Cheers
DD
You’d have to piggy-back some of your wires
You can make a common Chrysler relay work as well. Just have to change a couple of terminals. Typically about $20-25. NAPA number SR5
https://www.napaonline.com/en/p/ECHSR5
Cheers
DD
Could be starter relay. Could be ignition switch. Try disconnecting the battery and then twisting the key from OFF to START and back about 50 times to wipe crud off the contacts. If that makes no difference at all, it’s probably the relay.
The starter relay can be replaced with a Chrysler starter relay of similar vintage. The Chrysler item is a bit larger and doesn’t fit under the plastic cover too well, but it’s a LOT cheaper. You’ll also note that the Jag relay and the older Chrysler relays have a contact for bypassing a ballast resistor while starting, but your '84 doesn’t have a ballast resistor so that circuit is unused. Later Chrysler starter relays don’t have the contact.