No Start, Electrical Problem

To start off, I searched to no avail...

98 Cherokee, 4.0 AX-15

When I put the keys in everything turns on fine, radio works blah blah blah.
If I try anything with high amp draw, all electricity is gone instantly. This includes me trying to start the car, or even turn on the headlights. At first it would make a clicking sound but now it doesn't really even do that. This isn't a matter of charge on battery because I tried to get jumped and failed. I cleaned the battery terminals in hopes of fixing a bad connection, to no avail.
The whole ordeal is weird because it started up fine in the garage, I drive to the gas station through some snow, and bam no start after gettin gas.
Is there a relay that would cause such symptoms if it went bad?
Thanks in advance for the help.
Austin

Sounds like not enough transfer of current thru the battery cables to ground, the PDC and the starter.

Have you checked your battery cables to ensure they are tight, do they have corrosion on the battery terminals or oxidation in the wiring under the insulation?

If you have a VOM you can check voltages to the PDC and starter when you turn the ignition key to see what the voltage does.
The battery voltage should be 12.5-13.0V when the ignition switch is off.

Even though you tried jumping, this still could be a battery issue.

Have it "load tested".

Very similar to an issue I had. It was the Park / Neutral switch and after removing and cleaning it was OK. The starter realy is grounded via the Park / Neutral switch.
When you turn the key is the starting relay clicking?
If not, check the connector for the P/N switch. You should have a short between 7 and 8 (black cable and black/white cable) on Park and Neutral positions. The connector is located next to the gearbox dipstick. There are two connectors there, on my -98 it was the grey connector.
If you don't get a short in park/neutral then remove and clean the switch.
Lot's of threads describing how to do that.

As an emergency measure you could just wire the relay directly to ground. Just remember to keep the gear in park or neutral when starting.

RenegadeDude said:

Very similar to an issue I had. It was the Park / Neutral switch and after removing and cleaning it was OK. The starter realy is grounded via the Park / Neutral switch.
When you turn the key is the starting relay clicking?
If not, check the connector for the P/N switch. You should have a short between 7 and 8 (black cable and black/white cable) on Park and Neutral positions. The connector is located next to the gearbox dipstick. There are two connectors there, on my -98 it was the grey connector.
If you don't get a short in park/neutral then remove and clean the switch.
Lot's of threads describing how to do that.

As an emergency measure you could just wire the relay directly to ground. Just remember to keep the gear in park or neutral when starting.

Click to expand...

AX-15 Doesn't have one of these, I will try these other things and get back with you guys.

Check the battery cables and grounds, but you might be looking at a bad battery.

old_man said:

Check the battery cables and grounds, but you might be looking at a bad battery.

Click to expand...

I didn't think that having a bad battery would cause the electricity to completely cut out but since everyone keeps telling me I would be foolish to pass up advice. The battery is 6 months old... I visually inspected the grounds on the block and sprayed them with cleaner, where are the other ones located (besides fender of course)?

Electrical 101:

1. Make sure the battery is fully charged, then have it load tested. If you don't, everything else you try and do could just be P/ing into the wind.

2. With a fully charged battery that has passed a load test you need to do a voltage drop test on the main cables: http://www.aa1car.com/library/voltage_drop_testing.htm

3. Make sure all of the unibody grounds are clean and tight.

That should get you to the likely cause of the problem.

Note: a bad battery usually won't let you get going with a jump, so your hypothesis that the battery can't be dead/bad because you can't jump it is wrong.

Note: There is a clutch switch to prevent manual transmission equipped vehicles from cranking unless the clutch is depressed. I don't know if your XJ has that, but neither a NSS or a clutch switch would explain the lights not working.

ausi02 said:

I didn't think that having a bad battery would cause the electricity to completely cut out but since everyone keeps telling me I would be foolish to pass up advice. The battery is 6 months old... I visually inspected the grounds on the block and sprayed them with cleaner, where are the other ones located (besides fender of course)?

Click to expand...

There should be one that bonds the motor to the chassis, I'm unsure on a 98, you should not just clean them, you should take them off, wire brush the connector and the chassis and then reinstall.

joe_peters said:

Electrical 101:

1. Make sure the battery is fully charged, then have it load tested. If you don't, everything else you try and do could just be P/ing into the wind.

2. With a fully charged battery that has passed a load test you need to do a voltage drop test on the main cables: http://www.aa1car.com/library/voltage_drop_testing.htm

3. Make sure all of the unibody grounds are clean and tight.

That should get you to the likely cause of the problem.

Note: a bad battery usually won't let you get going with a jump, so your hypothesis that the battery can't be dead/bad because you can't jump it is wrong.

Note: There is a clutch switch to prevent manual transmission equipped vehicles from cranking unless the clutch is depressed. I don't know if your XJ has that, but neither a NSS or a clutch switch would explain the lights not working.

Click to expand...

it should have a clutch switch, simply jumper a wire from one pin to the other on the body side of the connector to bypass.

There is a Starter Relay in the PDC. Swap it out with the Fan Relay, to see if perhaps your relay isn't the problem.

Check the other relays as well.... Fuel Pump, ASD, Starter, and Fan Relay. I recently had a bad Fan Relay that broke apart internally, and was preventing my '98 XJ to start up. Check all the relays. Disconnect the positive terminal from the battery for at least 5 minutes, to reset the computer.

Bench test your starter. My XJ showed the same symptoms as yours, which made it appear to be a batter issue. It turned out to be a bad starter. Took all of 20 minutes to replace the starter.

You can also by pass the clutch interlock just to make absolutely sure that is not the problem. I found a green connector with yellow wire just looped back to the same green connector. It was taped under the dash right next to the clutch interlock connector. To my surprise the factory included this bypass under the dash for you. You just unplug the green connector with the yellow wires and plug it into the other green connector, with the yellow wire looped back to itself.