More weird electrical problems

I love my Jeep - but the wiring really is crap, based on what I read here and the fact that my remote and central locking wiring has so far baffled me...

Anyway, todays problem :

A couple of months ago when I 1st got the Jeep it was fine. Then one morning, the battery was dead - completely dead, as if the lights had been left on main beam for 24 hours - took 24 hours to charge the battery (my charger usually does the job in 8).

Realised later that if I leave, say the lights on when I shut down and remove the key, they don't switch off unless I restart the engine, shut them off and then shut down and remove the key.

Ever since I have diligently shut everything off before shutting down and removing the key and everything has been perfect - runs really well, starts 1st turn of the key, etc until this morning......

Battery completely dead again. Not a problem as it is not my primary drive at the moment, more of a project - so I see this as a challenge - but so far am baffled as to what it can be.

Any suggestions?

Martin :banghead:

You need to look it over good.
First check battery cables and grounds.
Then check condition of battery. A bad cell will kill a battery after it sits a while.
Then check charging system for good voltage and amps.
Then get a volt/amp meter and start checking for amps draw at post battery cable. With key off.
MT

Think I am OK on the 1st 3 but will check anyway once I get some power back.

Will start carrying a meter too so I can check every time I leave it that it is not draining - but very odd. Am struggling to think what would cause such intermittent behaviour - there are no separately switched devices dependant upon relays powered by the ignition circuit are there?

Martin :headshake

Not many switches. Head light. Brake light. glove box light switch. Starter solenoid. Door dome light switch.
But a lot of relays that could stick on.
Also alt diode. Cigreet lighter.
You may have to check the amp draw several time to catch it.
Good Luck.
MT

My 89 cherokee does the same thing with the headlights. I have to shut the lights off before the jeep, and the driver side door dosen't turn the dome light on when it's open, which i hate. as of now, it seems like its either my ecm or crankshaft sensor that's causing my troubles. But i'll find that out tomorow. Thank god i work at autozone or else my jeep, which i love, would never run!!

Let me know what the garage says - not sure how the ECM or crankshaft sensor would cause that sort of problem - but with Jeep electrics nothing would surprise me!

Martin :grinno:

OK - Have some charge in my battery, have put it back into the vehicle and reconnected the earth connection.

If I then run a voltmeter between the positive terminal and the battery cable, I pass a current.

I have pulled each of the fuses under the hood individually and re-tested. In every case a current still flows.

When I get back, I'll do the same with each of the fuses under the dash - but can someone tell me if all power feeds are fused please. And if not, how else can I isolate the device which is draining power while everything is apparently switched off.

Thanks, Martin

How many amps is it drawing?
You will just have to keep unpluging and unhooking untill you find it.
MT

Good question - am using a voltmeter at the moment just to show whether there is a circuit or not.

Will grab an ammeter as that ought to point me at the rogue circuit more quickly.

Thanks!

You def. need an ammeter to test that draw...how are you measuring to see the voltage? Not across the battery right? B/c you'll always get 12v there, even if the battery is unhooked. Your supposed to get 12v across the batt terminals. You need an ammeter or test light and put it in series, in other words disconnect the pos batt cable, put 1 lead of the tester on the post, the other on the disconnected cable, don't reconnect it to the battery. You want your circuit to be formed through the meter. Do not attempt to crank the engine with this connection though, those wires cannot carry starting current.

I think its normal for headlights to stay on a little bit if you shut the key off then switch them off...like a safety thing to light your way to your house front door or something at night. My 98 always has done it, and I like the feature, I just always look out the window after I get inside the house to make sure they have gone off (I think the time is like 2 min or so). So far haven't had them get stuck on, but I'm sure since its a relay and its' jeep wiring I'm betting someday they will, and it'll prob be the time I forget to check for them going out too. I currently am fighting with the weird gauge problem (gas gauge fails to register or registeres wrong sometimes, especially when raining). I know its a bad connection just don't really want to disassemble the whole dash to get to it.

Hope that helps.

Yep - was testing to see if I had a completed circuit by putting a voltmeter in series between the battery post and the battery cable (both positive)

My assumption is that with everything turned off this should not complete a circuit and no charge should flow - but it does.

Have an ammeter now, so as soon as some of this ice thaws I'll get out there and start pulling fuses and relays until I find the circuit which is causing the drain (hopefully steered toward the right circuit by the amount of current it is pulling).

Had not realised there was a 'lights stay on for a short while' feature - can't see it on the diagrams (but then again if Jeep wire their vehicles using these diagrams I am not surprised we all have problems :grinno: )

Thanks, Martin

OK - in answer to some of the earlier questions : the draw is around 0.2 amps, so nothing major but enough to drain the battery.

Definitely under the dash, as it stops when I pull the 40amp 'fuse box' fuse under the hood.

Nothing obvious / have not been able to isolate it yet / but draw jumps between none (0.0) and 0.2 as I fiddle with the wiring loom around the under-dash fuse board, so must be something in there.

Will let you know what I find.

Many jeeps have the safety feature that keep the headlights on after turning off the engine. The sequence is with lights on and engine running, turn off the engine, turn off the lights. The headlights remain lit for about 45 secs and then turn off automatically. If you do not turn off the lights, they will stay on (at least they do on my '88).

There is a small "push button" switch located in the door jambs that control all of the courtesy lights. If the switch is bad, none of the interior lights will work with that door. On my '88, this switch merely grounds the circuit, so testing the switch is real easy.

Last, there are plenty of reasons to draw power from the battery when everything is "tuned off". I have power door locks with remote entry. They need power all the time. If you have an alarm, it needs power all the time. Depending on your radio, it needs power to maintain presets. Often this comes from your car battery. And so on.

With the engine off, you'll get battery voltage (about 12v) across the battery terminals (in Parallel, not series). With the engine running, at idle, you should have a higher reading (mine hits 14.4v). With A/C running at max, headlights on, radio on, hazard flashers on, and rear window defogger on, mine dropped to about 13.5 v.

Thanks Saudade - that helps - but also makes it really hard to work out what is causing the battery to go flat occasionally.

I got a local auto-electrician recommended to me, so gave him a call to ask him to have a look. Was very surprised and amused to be told that he never touches Jeeps or Rovers - had too many problems with the wiring on them in the past and not worth the hassle.

He obviously does not like a challenge :lol2:

I really don't know what the issue is. I've worked on the electrical system of lot's of cars and it's the newer ones that I think are more difficult. There's WAY MORE wiring, more computer control, little to no access, and (IMO) the worst, is the declining skill in technicians to troubleshoot and isolate problems. I heard a guy (at Pep Boys) once say, if it doesn't show up on their scan tool as a problem, then it's not a problem.

Again, check the voltage across the battery terms, with the engine off, the engine idling and the engine racing (around 2500-3000 rpms).

Are you sure the 3 items from MT are ok? How did you test them? Weak batteries sometimes do strange things. All it takes is one bad cell.