New optima battery install results in dead short at the terminals. where to start looking?

The only wiring disconnects were to the heater fan and the relays mounted behind the battery on the wheel well. Have I got something backwards?

Hi Joe …… I think we need a lot more information here

Not much pre-event info to share. Battery box area in a LHD 70 OTS cleaned out to replace LH forward sill closing panel, forward outer sill and clean up surface rust in that area.
Left hand under shield, lefthand mud shield, battery tray carrier bracket and heater box/fan removed.
That job went smoothly (Thanks Chuck at Monocoque for perfect fitting parts) but when I refitted the new battery and tried to hook up the terminals all hell broke loose at the battery terminal posts. Looked like the Fourth of July.
It is possible that I’ve hooked the connections to the one or both of the 6RA relays improperly. I’m going over the wiring diagram now. There are two attached to the mud shield. One is the alternator relay I believe but I’m not sure what the other one does. The car is equipped with A/C. I’m trying to clean the insulation on the wires to try and identify them. Any tips on a safe method to clean them?
Anyone have experience with an internal short in a new battery? What were the symptoms?

On a S1 there is just one relay there and it is for the horns. I imagine one of yours is as well as it’s a high amp circuit. Does the alternator have its own relay? My bet is that you’ve wired them incorrectly. I don’t see what else it could be from your description.

DeoxIt spray works to clean terminals.

Joe
If your battery had an internal short it would be dead . For years I’ve used brake cleaner for contact cleaner ( save your money :moneybag: it’s good starter fluid too and cheap ). If they’re really dirty wire brush or small file first.

Somewhere you’ve wired positive to ground look for burnt wires hope you just touched it. Use an ohm meter to trace it . I get the impression the car was worked on by someone other than you? they may have taken wires off that your not aware of
Cheers. Jim

Any chance you got the battery polarity backwards?
Tom

Thanks for your reply Erica!
I never thought of using Deoxit. I suppose the version I use on my audio and guitar connections would be good. See any problems using this version.
Although I’m not aware of any gold used in the connections, the current price of anything Jaguar leads me to believe that everything is at a minimum plated if not solid gold!:stuck_out_tongue_winking_eye:

I would expect you to find 3 relays there: Horn, alternator and AC (top to bottom). But if the AC is an aftermarket (not factory) then that relay could have been fitted elsewhere.

1 Like

The A/C appears to be the factory version that the housing always cracks on and are impossible to find. I acquired the car when it was less than 2 years old so I’m not 100% certain. That I know of there have only been the two that are currently present. I’m trying to clean 52 years of road grime now to see if I can make anything of the wires identifying markings. One thing that has been changed that I failed to mention is the wiring associated with the Pertronic ignition system. I’m backtracking now to see if I can figure out this wiring schematic and track this down. Thanks for your reply!

Unless the case is marked in error, I don’t think so.

Nope Jim, I’ll have to take all the blame on this one. Reviewing the schematic now to try and identify the problem.

If your ignition switch was on so there’s a load ,the battery will spark a little when hooking up the terminals . A dead short will fry wires within seconds.
Also there’s an insulator on the battery cable connection mounted on top of the regulator mount it’s made of plastic could be broken as they get brittle with age
Cheers. Jim

1 Like

I use two different contact cleaners. One is just your basic contact cleaner. The other is a contact cleaner with lubricant. You have to let the electrical parts sit overnight or at least a few hours after you use it. It’s great for bringing crusty but not yet broken switches back to life. I’ll have to get a photo of it next time I’m with the old S2.

1 Like

Joe,
I find redrawing the circuit that I am investigating and using colored pencils helps me a lot
I know they have diagrams in color too
But I like to redraw it on a nice big piece of paper and isolate it.
I have a simple mind

1 Like

Is the care negative or positive earth, and does this have an impact on the battery connections?

1 Like

ANOTHER guitarist! I swear…:stuck_out_tongue:

2 Likes

We should start a band! We’ll need a catchy name and a promo picture.
That’s the sure way to guarantee we would only play one show before the band broke up.

1 Like

Negative earth. A little too much earth at this point.

1 Like

Not so simple minded if it works. I’ve already pulled out highlighters in a rainbow of colors. The biggest problem I’m having is identifying any distinguishing coloring on my wiring harness. I’d swear this car has a wiring harness that is not factory. I am at a loss to explain the lack of ID, but entire circuit groups appear to have all black wires while the schematic shows the usual W/B, NP and so forth. I’ve owned this car for 50 of its 52 years and can’t imagine a wiring harness needing replacement during its first few years. Anything is possible I suppose, but I’m assuming the circuit colors were on the cloth wrap and have disintegrated.

Are you referring to the black boot or the whiteish insulators either side of the VR mount?