It's late and cannot work on this right now but I've been thinking about a couple problems I have ....I recently bought a 1999 Cherokee Classic and it has a couple problems I need to fix... One problem is an intermittent burning plastic smell... Occasionally, I get the smell of burning plastic inside the vehicle... But not every time I drive the vehicle.. I've looked but so far I haven't been able to find out where the smell is coming from... And I have looked. I also haven't been able to find any wires or connector that look burnt or feel hot...Nor have I figured out any pattern to when I get the smell. However, I just recently started having another problem that may be related....

The last three or four times when I started the vehicle when it was cold, the motor turned over slowly.. but started up... So I didn't check it out other than look at the in cab voltmeter.. With the engine running it shows 14 volts... with the engine off it shows about 12 (which I believe is normal)..

Today I hadn't driven it for a couple days and went to start it up.. It wouldn't crank over .... The starter just clicked and the interior lights were dimmer than usual... When I used a set of jumper cables, It started right up..... The battery was flat... Not completely dead but not enough charge to spin the starter.. I know I hadn't left any lights on. Right after starting the motor I put a digital multimeter across the battery terminals.... It showed 14.10 volts... when I pressed the gas pedal, it showed 14.26 volts... After driving about 5-8 minutes.. (it was dark so this was with the headlights on), then parking for about 45 minutes, the engine started right up. So the charging system is charging...

I was told that the battery was replaced earlier this year. It looks new but it may not be... So, my plans are to pull the battery and have it tested..
If the battery is bad, that could be the cause of the second problem.. (but not the first)

However, I wonder if the problems could be related??? Perhaps there is a problem with the charging system that is causing the smell... or... maybe there is a problem with the ignition switch... or... Maybe burnt insulation somewhere is acting as a high resistance short and draining the battery??

Bobby

 

I would check the headlight switch and the blower switch on the heater controls. The headlight system in our XJ's isn't that great and the only time that I got that burning smell, it was the connector on the headlight switch and I've gone through 3-4 switches in two different XJ's. The blower switch pulls a lot of juice and I have melted one of those before but never enough to get the smell.

 

This is a good place to start once you replaced you battery. Also check the blower motor resistor. when mine was getting read to go out I also smelt burning plastic and that's where it was coming from. Just because you think the battery was changed this year doesn't mean it can't be bad. Have it load tested.

 

x2 on the headlight switch and BMR. Also, do you have factory foglights and use them? That switch might be to blame too, although not as likely.

 

(cant help with the burn smell thing)

Relating to the battery issue, in cases like this, do basics first: have the battery load tested. If you find that your battery over time seems to be draining and you have no idea why, this link might be of use to find if you have current drawing from it.

 

Before condemning the battery, have you load tested it? Have you made sure all of your grounds are clean and secure?

 

If you smell something burning I'd suggest picking up a fire extinguisher. Seriously, not a bad thing to have handy anyway.

Battery gasses have a nasty habit of helping a thin, hard crust form on the bat post's and clamps. They can look pretty good, but that micro-thin layer is a surprisingly good insulator. SHINNY! Lead is what you want. I use a pocket knife, (gently), for the insides of the clamps. For the posts I might use one of those post cleaner wire brushes, but still scrape it with a blade. If you have a condition where you have power, (dash lights ect.), then when you hit it power goes out altogether, that's a common result of a layer of oxidization there. Btw, a half *** connection could be expected to get hot during cranking, or while it's trying. Cleaning those is something to do now and then anyway, so if you are having starting problems, you might want to make sure you have bare lead on lead. Might save you some grief!

 

I charged the battery, removed it and took it to the local "Batteries Plus"...they tested it and found it good... After sitting for a while (24 hours) it still showed over 12.5 volts and their test set showed a CCA of 824A on a battery rated at 800 CCA... So I have to look for whatever is draining it... Will try and do that tomorrow

 

Check all of your grounds, wouldn't be surprised if that's it. Also make sure none of the cables including the battery positive are front at all. If you have an aftermarket terminal that just bolts a plate down against the cable... those are junk and can cause issues if they aren't soldered, even so they aren't totally reliable. Also check and see how many amps are charging the battery, and see if the alternator is in full field mode. These issues can cause a constant burning smell.

 

Being a "pest" here has proven right a few times. Really those connections can look just fine, but that micro thin layer needs to be scraped off to have bare lead on lead.

One stagey to find a bleed is to remove the fuses, then see which one dings the voltage when it's back in.

 

How about you scroll back up and check my post #5 and do that?!