Will not start (help please)

Hello Steven:

Success. When I thoroughly cleaned the engine to chassis ground cable connections, the car started. Thursday was a glorious day, (78F), so I put the top town and went for an extended ride.

Good thing. This morning it is 33F here with snow. Yes, one month into spring and it is snowing again. Ugh.

Thank you for all the help getting my car back into full operation.

Best regards, Bob G.

Hello Steven:

EUREKA.

When I connected cables from my truck to the XJS battery, the car instantly started. No hesitation, no measurable time for cranking.

Thank you for staying with me during this exchange. Your patience and insight are invaluable.

Lessons learned:

1) a two-year old battery can fail.
2) When my mechanic told me (in January) the starter motor is shot because he measured high resistance, replacing the starter motor-solenoid, while helpful on an 18 year-old car, was not the solution to the problem
3) Failures on Jaguars with 75+ relays are difficult to diagnose.
4) Always trust Steven Petry.

Thanks again. I'll be replacing the battery tomorrow.

Very respectfully,
Bob G.

Good afternoon Steven:

Thank you for confirming.

It has warmed to 34F today. The driveway snow has melted. I plan to use my truck to try to jump start the XJS this afternoon. Success would be great, A start will tell me to go buy a replacement battery.

I only start and drive the car every 3-4 weeks in the winter. There were some hints. Some starts took a little longer than I thought was normal, then nothing ... just clicks. First replacement was the starter-solenoid. It worked fine a couple of times. Now, the clicking returned.

I'll let you know the outcome.

Very respectfully, Bob G.

Absolutely a weak/failed battery could substantiate the clicking you have. Which is why we need to establish the voltage at the battery terminals when it occurs. That will point us to the battery itself, of somewhere else in the car.

Hello Steven.

If it ever warms up, I will try battery cables from my truck. The recent four inches of snow needs to melt first. I live alone, and do not have anybody local who could help me with a voltmeter.

So, this surfaces another innocent question. If you do not mind me asking, let's suppose my two year old battery is at fault. Could a weak battery fail to energize the starter solenoid, and lead to the rapid clicking sound that I have described?

Thanks again for helping. As always, it is appreciated.

Very respectfully,
Bob G.

That sure sounds like the battery, Robert. The battery itself, or the battery cable that runs the length of the car.
I would get hold of a volt meter and connect it to the battery posts. Then have someone watch the voltage as you attempt to start the car. If the voltage trails off just like the interior lights as you described, that confirms the battery is going away.
If the voltage stays around 10-12 volts as you try to start, and the lights still dim or go out, then the problem is in the battery cables or connections somewhere.

We'll make you a mech-a-nik yet.

Oh, yes, I should add --- once the power started to fail, the windshield wipers turned on, and I was unable to shut them off, except for the ignition key.

Hello Steven:

Well, the weekend ha arrived. I had hoped for warmer weather, but alas instead we had 5 inches of heavy and wet snow. I am sure it wasn't much different at your location.

Well, I received the replacement starter relay, removed the original (contacts were covered with green corrosion), and inserted the replacement.

Next, I re-installed the battery, fresh from a 7-day connection to a slow 2-amp charger.

Unfortunately, no luck. Initially, more rapid clicks, then what appears to be a rapid battery drain. The interior lights quickly dimmed, then the clicks slowed, and then nothing.

I am at a complete loss here. Any thoughts would be greatly appreciated.

Very respectfully,
Bob G.

Hello Steven;

You are a pleasure. The information always comes with a patient explanation. I can easily resell the SRB301 since it was used on many British vehicles, as well as the 71 and prior XJS.

I presently have the battery out of the trunk and connected to a slow 2 amp charger. This weekend I will swap the starter relay with the horn relay, assuming it warms up (I'm in Cleveland-area so I enjoy the same weather as your have in Indianapolis-area).

The clicking is a puzzle. I hear in from the driver's seat location when turning the key to start. The battery is new, the starter motor (with integrated solenoid) is new, and all contacts, wires, etc. have been examined, brushed, and have solid connections. The failure was sudden. No warnings, no evidence of degradation. I really hope for a simple solution like the relay.

I will let you know the outcome after the weekend.

Very respectfully,
Bob G.

Sorry I didn't get to this sooner. Your car does not use the higher priced relay. The SRB301, which was originally C36611 from Jaguar, was last used in the1991 XJS. From 1992 on the starter relay was a standard Hella relay. The DAC7686 was eventually replaced by P/N LHF6703AA which was a sealed black relay that better kept out the elements. Any standard 40 amp relay that has an anti-spike resistor across the coil will suffice here.

One thing you could do, since all three of those relays are the same, is swap one of the others for the starter relay and see if you can start the car. The starter relay is the one that has a good sized white wire with red bands.

One hint though, since you get the "solenoid click" when you attempt to start the engine, I suspect the relay is functioning.

Good luck!

Dear Steven Petry:

I ordered a SRB301, Lucas original equipment, starter relay from the UK. A picture is attached. It was about US$40 including shipping from the UK.

When I opened the hood of my 1995 XJS. I found the starter relay in the Right Front Component Panel as described in my electrical diagram book. This is a very different part. It is DAC 7686. This is a plastic cube profile, light blue and white. I also ordered this item, about $8. A picture is attached, index is #7.

I know how difficult this is to troubleshoot without seeing the car in front of you. Do I need to replace both items? (SRB301 and DAC 7686)? How do these two items differ in purpose, since only one starter relay is shown on the wiring charts.?

Lastly, I cannot find the SRB301 in the engine compartment. I really feel dumb. Could you please offer a hint as to where I should be looking?

As always, thank you Steven.

Very respectfully, Bob G.

As I see it, your batting average is .999 ----

Thanks again for confirming my thoughts on the starter relay.

I see prices from about $50 to over $120 for NOS (new, old stock), mostly converted from British pounds, plus international shipping .

XKS says the original part is obsolete, and offers a replacement for $55, plus shipping.

As before, your thoughts on using the replacement part from XKS.

Geez! This is embarrassing........

By all means, that relay should really have been #2 on that list.

Silly me, I'll go stand in the corner.

As always, Thank You Steven. You have always provided sage advice to me (and many others) before. I will re-check all you suggest.

I am also thinking the starter relay might be the root cause of the clicking. Your thoughts please?

Very respectfully, Bob G.

1. Reman starter is always a suspect.
2. Have battery load tested, could be failing at the instant the starter load is applied.
3. Check battery negative cable, esp. the end attached to the body.
4. Check the engine/subframe/body ground straps for looseness, corrosion and integrity.

Good luck!