Working on an XJ6 which has been worked on by somebody else... The alternator is new; not rebuilt. The battery tests at 93% of CCA spec so good.

The lightning bolt is on in the dash, and it is not charging.

There are two ~1/16" wires with round wiring flanges coming out of the main single-thick-wire wiring harness to the alternator. they are coming out of the wiring harness about 6" apart close to the alternator back.

Both are presently connected to an alternator terminal each. I am thinking that is wrong?

Ideas for how to test what each of the thin wires are for, please? One must run to the load dump module but I don't see that module. Don't know if the other one runs to the 100 ohm resistor.

I don't see a fuse on the wire from the alternator to the starter. Should there not be a power fuse in series?

I will post some pictures tomorrow.

Thanks in advance for any inputs.

Regards, Bo

 

Hi Bo,

You can download the wiring schematics here:

Jaguar XJ40 Electrical Guide 1993-1994

You should be able to identify the wires by color. See the color code guide near the front of the manual - not all of the codes are obvious (e.g. N = Brown, K = Pink).

There is no fuse in the wire between the alternator and starter.

I don't recall our '93 having the load dump module, but it did have a suppression module. The resistor you see may be part of that circuit.

Cheers,

Don

 

Thanks. The plot thickens. It is a 1993. However, I realized that it has the filter capacitor module not the load dump module. The filter capacitor is located at the very bottom front. It looks completely factory installed. It is a black plastic cylinder containing a large electrolytic capacitor. As far as I know, it should not have been on the XJ6 before 1995???? I am thinking that it was wired incorrectly when the alternator was installed, rendering it inoperative and probably the battery fuse? blew. Two questions, The brown positive from the capacitor goes to the same post that wires to the alternator. When does the black negative go on the alternator, please? Second question, is the 250A fuse to the battery in the trunk or under the bakc seat or? Thanks for your help.

 

Hi Bo,

Were you able to open the Electrical Guide? It clearly shows that your '93 has the suppression module rather than the load dump module. And no fuse between the battery and starter. Here's a snip from pdf page 30:



Cheers,

Don

 

Thanks for the help. The filter was definitely not grounded. I am bummed that there is no high-current fuse from the alternator to the battery as on later models as it is still not charging and the lightining bolt symbol is still on even with a brand new alternator and battery testing A-ok for voltage and CCA. Any thoughts on where I can go next, please? I am running out of ideas. The working hypothesis was that the not connected filter capacitor blew the power fuse. Regards, Bo

 

Hi Bo,

First of all, I'm wondering if I recall that the lightening bolt symbol actually means a blown fuse rather than a charging problem. Have you checked every single fuse in all three fuseboxes? In another thread, Larry has reminded us that the fuseboxes are known for cracked solder joints internally, so that could also be one of your problems.

Regarding the battery charging, have you cleaned the jump-start post on the firewall and the power connections at the right footwell fusebox? Those connections are in the circuit between the alternator/starter and battery and any looseness or corrosion can cause poor battery charging. Also check both ends of the battery ground strap and the battery negative cable connection to the body, since those complete the charging circuit.

Are you confident that you have the wires correctly connected to the alternator now?

What voltage do you measure across the battery posts with the engine running? Off the top of my head, I think it should be 13.6 volts or greater.

Cheers,

Don

 

I will try to explain it. You have 1 big lead going to the battery. That the easy one.

and than 3 small leads, (in 1 round connector I think). They have symbols IG, L, D (for Dummy). these letters should be shown on the back of your alternator, but can be difficult to see in the dark of an engine bay. Lookup a picture of your alternator on an autoparts website, usually they show which connections is IG, L and Dummy.

The IG connection should get 12v when turning on the ignition.
The L is for your dash light.
The dummy connection, you don't need it.

hope this helps

 

Thanks.