The Problem Is:


When the Windshield Wipers do not work, the Horn and Climate Control Motors also do not work. if (WHEN) the wipers come back on all of these components work.


Is there a common ground that may be disconnected?


Any Suggestions?


Thanks.

 

First suggestion: fully identify your car

Cheers and welcome aboard

DD

 

until you let us know the year and model specs you can always do a quick check at the fuse block to see if those share a fuse. In which case it could be ground but could even be a intermittent bad fuse

 

My car is a 1986 XJS V-12 with 40K miles on it.
All of the fuses appear good in all 3 fuse boxes.

 

"Appear good" isn't good enough

Horn, blower relays, and wipers all have something in common: fuse #11 in the LH (main) fuse box.

The fuse might not be blown the wire inside the fuse could be breaking away from the metal end cap. Also the metal end caps, and the clips that the end caps snap into, could be slightly corroded...very common. Lasting, the wiring/connections behind the fuse box could be loose.

If you need to replace any fuses, and still have the Lucas originals (with the paper label inside the glass tube) be mindful that the rating system is different.

Brit 50 amp is USA 30 amp
35 is 25
30 is 20
25 is 15
20 is 10
10 is 7.5
5 is 3


Cheers
DD

 

who the hell came up with a different definition of ampere?

 

The ampere definition remains unchanged . Only the the fuse design and rating method differs.

The difference is 'continuous rating' versus 'maximum rating' or something like that. I can't remember the details.

Someone who remembers will come along.

Cheers
DD

 

What the hell? An Amp is an Amp is an Amp, Doug are you trying to tell us that between the European spec cars compared to to US spec cars there is some sort of difference between the wiring or or how much the electrical draw is that its component is running?
I realise US mains are 110v and ours are 240v and there is a difference in sound amps in the guitar world, but both the darn cars run on 12v, sorry this you have to explain a little more.

 

Sorry must of posted at the same time , you just beat me too it. Interesting!
The only explanation I can come up with is that start up currents are much higher than run currents, I wont go into detail but they must be taking that into consideration. example a motor will draw a lot more amps at start-up then when running, or a fluorescent light will do the same. still very weird to have both ratings in a car!

 

I read this as the way the Brits may rate their fuses.

Amps are amps, there's no denying that, however the way someone decides to rate a fuse may be altered depending on what tests would be required.

USA testing may differ from UK testing.

 

"Like so many other things about our Triumphs, the British did things just a little bit different than the Americans, including what the ratings marked on fuses mean. The British Standard that Triumph used rated fuses by the current that was guaranteed to make them blow instantly while the American (and now international) standard rates fuses by the current that they will carry forever."

Tim Buja and Glenn Merrell put on a good visual demonstration of the difference in fuse ratings at VTR this year, where they first put in a "25 amp" Lucas-equivalent fuse and applied enough load to blow it. Then they installed a "25 amp" American fuse and applied the same load. The fuse did not blow, but after just a minute or so the wire started visibly leaking smoke...

English Type American Standard Replacement
50 amp AGC 25
35 amp AGC 20
30 amp AGC 15
25 amp AGC 15
20 amp AGC 10
10 amp AGC 5
5 amp AGC 3

 

either way i don't know what you guys are talking about. The XJS uses standard fuses. Do the older ones actually use the tube/paper type?

 

Right! Either 'standard' glass fuses or 'standard' plastic/blade fuses :-)

1987-older use glass fuses. 1988-newer use plastic blade-type fuses.





Yup!

Cheers
DD

 

all I really have to say is "lol"

 

You might call the glass fuses a stubborn refusal to keep up with the times. Or you might call it a satisfying nod to tradition...you know....charming and quaint and all that

I'm 99% sure that the last of the Series III sedans built in 1992 still had glass fuses!

Remember, there is no such thing as a design flaw on these old Jags. Some things might *look* like a design flaw but they're actually "interesting engineering features"

Cheers
DD

 

Oh dear! not sure to either cry out with laughter or just cry as I know now a little more to what awaits me. LOL
Yes definitely "engineering features" for a car so advanced it really is sooo backward.

 

Weren't the glass ones call pontoon fuses?

 

Doug,
Thanks for the fuse tips! I was having the same issues when checking my fuses. My low/high beam right lights on my 84' XJS V12 tend to go out on low but when I switch to high they both work. Orignally I purchased a headlamp to solve that issue and the new one did the same. FUSE. I would never imagine the little wire at the cap would be separated.

 

Never let your guard down with these cars. Check my post under non working windshield wipers. Never ceases to amaze me. Tell me again why we own these cars?

 

Being a sparky this has bugged me for a while but I think I have found the answer:

The current rating on the British fuse is the value that will cause it to blow.

The American standard quote the value of current it draws whilst in use. This is its continuous current.

So if a particular circuit draws 1Amp in its normally operation, you use an American 1 amp fuse but you'd use a higher rated British fuse for the same circuit else you would always be blowing your fuse.

American - Continuous Value
British - Overload value

Working back the other way...if you have a circuit that is protected by a 2Amp British fuse, youd have to use a lower rated American fuse, as otherwise you'd be letting it operate right up near its overload rating, and maybe even melting the wires before she blows.

Also...on AGC