Tonight I left my headlights on for a couple minutes on my 1998 XJ and went to start it and no crank, voltage guage showed around 12 volt.

I have a deep cycle battery that I keep charged for my RV and I connected it with jumper cables and still no start. I was convinced that the starter relay decided to give out (occasionally I would have a no crank situation like this, usually if I stop for a bite on the way to work before the Jeep had a chance to run for a while, but I have always been able to convince her to start).

Here is the weird part. I decided to go ahead and connect my battery charger and after a few minutes on the charger it started up. I let it run for a minute, shut it off and tried again (charger disconnected) and no start again. Connected my digital meter at the battery and at rest the battery has 12.4 volts and with the key in the crank position, it only drops to 12.24 volts. I have quite a bit of auto electrical experience and I know that a car will crank with 12.2 volts but my problem still seems to be voltage related. All there is between the key and the starter is the transmission position sensor and the starter relay.

The transmission position sensor is new and adjusted properly. My battery terminals are in good shape, tight and no corrosion. My guess is that voltage is dropping somewhere downstream of the battery due to a connection or something. Is there anyone else that has experienced a similar problem? I know how to troubleshoot, I could use some starting points, where is the starter relay, is it in the power distribution center under the hood? Are there any connectors that are common problems on the XJ that could be a weak link?

I also have intermittent non-operation of the door locks and passenger window. Maybe this is all related.

Thanks

 

How did you adjust the transmission Neutral Safety Switch? Have you tried starting in Neutral?

It's the starter solenoid that I'd take a look at next for troubleshooting purposes, mounted on top of the starter.
See post # 13 here:
https://www.cherokeeforum.com/f2/sta...-issues-29806/
Along with both positive and negative battery terminals, connectors and cables, and power and ground connectors at the solenoid.

If that all checks out, have the starter tested. Is it soaked in oil, by chance?

 

if the voltage is only dropping to 12.24v when you go to crank it, its not even trying to start. in othter words, no power is making it to your starter.

that means you either have a huge voltage drop somewhere or a switch/relay is not closing the circuit. or possibly an open in the starting system circuit wiring, fuse, etc.

check your starter connections & battery terminals for looseness & corrosion. if that checks out, bypass the starter relay to test for a defective ignition switch. (when removing the starter relay, the pin terminal you will want to apply 12v to will be the one closest to the passenger side fender, i forget the number).

also try wiggling the shifter in P or N while trying to start it.

 

that right there suggests a voltage drop between the battery posts and the terminals; I.E, battery has sufficient voltage but is unable to make it past a cruddy terminal. then when you connect a battery charger to the outside of the terminal, you bypass the crud/corrosion which is why it can start.

have you removed the terminals to check for corrosion inside?
check the battery voltage at the (+) post, and on the (+)wire directly past the terminal. voltage should be the same. if you see a drop there is your problem.

also, what kind of shape is your battery in? what is battery voltage with the engine running?

 

I hear what you are saying and this was my first though, however, if the connection between the posts and the terminals were cruddy, then connecting the new (fully charged) deep cycle to the terminals would have allowed it to start. I guarantee the terminals and posts are in perfect condition. I agree with you that the voltage is dropping but it is dropping somewhere downstream of the battery. I am sure of this for a couple reasons.

1. in the crank position the battery reads 12.2 volts BOTH on the posts and terminals with or without the 2nd battery connected.

2. I can swap with a brand new battery and the condition remains the same.

The only thing that affects the condition is supplying the additional voltage of the charger (around 14 volts), it works 100% of the time at 14 volts. This tells me that the trans position sensor and ignition switch are not at fault and that the additional voltage is enough to overcome the voltage drop.

I have troubleshooted many electrical systems and I am sure the voltage drop is somewhere past the battery. I just need to figure out where. I appreciate your good advice, it is right on the money, it is just not the battery or battery clamps, it could even be the cables themselves, they could have corrosion inside. I have seen this before where you can't see it at all until you cut off the insulation. I am going to start at the cables and work my way down. The reason that I had a feeling that it was a factory connection somewhere is because of the other intermittent electrical issues. Thanks for the info, I will track this bad boy down this weekend when I have some light (was working on it in the dark last night) and post my findings.

After this the XJ is going to get a dual battery setup with new cabling and switching. I hate being stranded because of battery problems.