ive been having starter motor issues. but before i go tearing into the bowels of the car i was checking other potential sources.
this is not of "major" concern, but there appears to be a wire connecting to the starter relay that is not documented on the electrical diagram.
car is a '91 5.3L
i'm attaching an image of the circuit diagram.
all of the colored wires match up to what is in the diagram, except for one.

- a white/yellow small gauge wire is documented to connect to the W2 terminal in the diagram
- this is what is on my car
- there is another small gauge wire, white/blue, that is also connected to the W2 terminal on my car
- i don't know where this comes from

if anyone has a clue what this might be let me know so i can be sure to check all possible failure sources


--------
the other connections at the relay are
- C2 terminal: brown, battery
- C1 terminal: white/red, starter solenoid/motor
- C4 terminal: white/red, EFI
- W1 terminal: black/green, neutral switch

 

The white/blue appears in some of the older (like 87-88-89) XJS diagrams as 'not used'.

On some of the even older Jag models it was used to provide 12v to the ignition coil, bypassing a ballast resistor, when cranking the starter.

Hoepfully others will chime in but if you're having a 'no crank' problem I doubt that the white/blue wire is important. It'll provide 12v when cranking to whatever it is hooked up to....if it is hooked up to anything at all. But I don't see it as anything that would *prevent* cranking.

Let's wait for others.


Cheers
DD

 

Correct me if Im wrong. If the wire is used to bypass ballest resistor during start, wouldnt it provide approx 8.5-9.5 volts while cranking? Not 12v as stated.

 

thanks for the clue.
i don't think the wire is germane to my problem. but thanks anyway.

my problem by the way... is... that when i connect the battery terminals, it sounds like the starter is spinning, but the solenoid has not moved the actuator.

the fact that this happens without the key in the ignition makes me think that the starter relay, or the ignition switch may be the issue.

its hopefully that, and not that i've either fried the solenoid on the starter or i've got corroded/shorting terminals on the solenoid on the starter motor.

 

On models that use a bypass resistor the voltage supply to the coil goes thru the ballast resistor for normal engine running. The coil gets about 9 volts or so.

However.....

To make engine start-up easier/faster the ballast is bypassed so that the coil gets a full 12v when cranking the engine. To do this voltage is taken from the starter circuit (in Jags from the starter relay) and applied directly to the coil.

Won't matter in this case, though, as this model does not use a ballast resistor, bypass type or otherwise.

Cheers
DD

 

Remove the white/red wire from the starter relay. If the problem goes away then you know the problem is upstream of the starter...relay most likely. If the problem remains the you know the problem is not related to the relay or ignition switch

Cheers
DD

 

thanks doug. will try that next.

also, figured out the white/blue wire... from mr. palm's book:

"The C4 terminal doesn’t do anything on the Lucas relay, and the BAL terminal won’t do anything on the Chrysler relay.

Not only is the C4 terminal still there, but the WU wire that went to the ballast resistor is still there as well -- at least on this author’s ‘83. In fact, there are two WU wires; one is connected to the C4 terminal and goes nowhere; this is the one that used to go to the ballast resistor on the OPUS ignition system. The other WU goes to the cold start timer, but it
doesn’t connect to the C4 or BAL terminal; instead, it is connected to the W2 or G terminal along with the WY wire."

i think i even read this 2x before starting tinkering in there. the white/blue i was referring to is the second w/u kirby mentions. connects to the cold start timer i suppose.

 

I'm not so sure.

I'm fairly certain that Kirby was referring to the "Thermotime" switch that controls the cold start injectors. However, your car does not have cold start injectors.

I'll do some mulling as to what other timer/device might need '12 volts when cranking'

Cheers
DD

 

oh.
so there may be 2 vestigial white/blue wires.

i'll get in there this weekend and report back.