Hi all,

I have a 94 XJS 6cyl. I recently replaced the Fuel pump and filter. Got it all put back together. Went to test it and the battery was dead. If figured it was due to not being cranked for several weeks (it took me a while in my spare time to get the old pump out and the new in). Got it charged cranked it up. No leaks. So took it for a spin and it died inconveniently far from home. Got it jumped off and took it home. Put it on charger again. Took it around the neighborhood and it did fine.

Tried this again yesterday and the same result. When I'm about a 1 mile or so from home, come to a stop sign it shuts off and the battery is dead again.

This morning, while attempting to go for a new battery, I jumped the car up and got it going. Sat in the driveway for a long time to let the system charge up. Got a bit further from home and the same result. Fortunately a good samaritan saved me from a long walk home and jumped me up again.

So when I got home with it I did the ff code and 69 came up which indicates low voltage. Otherwise my charging system indicates that it's charging as it should. Would a dead battery cause this even if the charging system is ok otherwise??

I also checked to see if the trunk lights might be staying on, but they don't.

I am also getting the transmission warning light as well. However it is not as consistent. Even with the trans light the car is shifting as it should. Does any of this have anything to do with the battery?

 

Dying batteries caused me a lot of grief. Swap out the battery, and see what happens.

Not sure if it would have anything to do with the transmission light, but I wouldn't be surprised if it did.

Dying batteries prevented my power locks on the passenger side from working...sometimes. The horn would also not work... sometimes. It would need to be jump started....sometimes.

These cars need a solid battery. Once it starts to go downhill, a bunch of weird things start to happen. Swap out the battery and then let's see if that transmission light comes back on.

 

If your battery was flat after several weeks of inactivity and barring a defect in the car, it's time for a replacement.

Running a car at idle will not effectively charge a battery, it's also very hard on the alternator.

 

Before you convict the battery and toss it, try the following.


1. With all switches off, remove the ground cable. Connect A VOM in series. Read micro amps. Any more than a "few"? If so, a parasitic drain exists. Any battery will go flat, just a matter of how much time.


2. Make or buy a device to read volts at the cigar lighter outlet. Check volts under various loads and rpm's. Is the alternator able to "keep up" or lag til the battery gets too low to sustain the loads.


3. Remove and clean the battery cables on both ends. + and - .


4. Find the chassis to transmission/engine. Clean and lube it ant both ends and nce and tight.


5. DIY load test. Turn on a lot of loads, including the lights. Fire the engine. Do the lights dim at idle and brighten at rev's? Indicative, but not altogether dispositive.


6. Tough. Ignition off. Jump the starter. How long can it crank Caveat, too much can kill a starter.... But. if after a few cranks, it poops out, it failed a rough load test. Sulfated, done for or well on the way....


Carl

 

Parasitic current drain can be up to 50-100milli amps especially if you have an alarm, 20mA is typical and at 50mA a large car battery will last approx 5 weeks without charging.

Check your charging system.

Start the car and measure the voltage across the battery it should be 13.8-14.4volts anywhere in this range your alternator is working.

Lead Acid Batteries are damaged by deep discharge sometimes to the point where they never recover. If you do not use your car regularly it's a good idea to have a smart charger hooked up to the battery. I use a C-Tek and it can be connected up without disconnecting the battery from the car.