Hi there-

I have a 1998 V8 Grand Cherokee and have been having a heck of a time with the battery. It keeps dying for no reason. I have read several posts regarding this problems with relays and such.

I can jump start it fine. Tonight I tried to jump start and it would not stay on. Battery and alternator tested fine. No lights on inside. About a month ago the alarm would go off for no reason. Factory alarm and keyless entry....

Had all wires from and to battery changed. Reset the alarm as suggested by dealer.....

Please... any help would be greatly appreciated.

Jump started it. Took it around the block. Turned motor off and then was not able to start. Dead again....??
Almost at wits end....
Thank you.

 

jump and drive around the block will not charge the battery, needs driven, preferably at 45 mph or higher for about 30 mins

 

mcssis is correct in that you need at least 30 minutes of vehicle charging to be able to restart from what was a flat battery.

I would suggest you buy a DC current clamp (such as this one available from ebay sellers).

http://cgi.ebay.co.uk/UNI-T-UT203-AC-DC-AMP-clamp-current-METER-UT-203-/250722687759?pt=UK_BOI_Electrical_Test_Measurement _Equipment_ET&hash=item3a603c9b0f

The important function of the clamp is that it can measure DC current – many cheaper current clamps are available but they will only measure AC current via the clamp.

Once you have such an instrument, place the clamp over whichever battery lead (+ or -) is easiest (ensuring you clamp all conductors from that battery terminal) – the meter will then display the current flowing from your battery.

To be draining a battery overnight the battery must be draining at least an amp. It is then a simple matter of pulling the fuses in turn to determine which component is draining the battery, and taking corrective action.

Note that with the hood up, you may have engine bay lights on – which will need to be removed or the switch supplying juice to them overridden.

 

Took out all fuses and were good. Checked the tow package fuse and was still drawing current. Took the fuse out and stopped the current. Put back in and still drained the battery. Left fuse out and still drained the battery.

It is in the tow cluster. Now what else could it be from this point?

Battery and alternator are both fine????

 

Could be anything two posts up is what needs to be done. That is what a repair shop would do.

 

It would be useful if you can supply the errant current drawn by the tow pack.

From your description of the fault, you either have two battery drain paths (one which is intermittent), or following pulling the fuse (supplying the tow pack), there was insufficient charge in the battery to start the vehicle (after a period of time) – which you have misinterpreted as battery drain.

My bet would be on the latter, but it could be two drain paths.

In order to determine which, I would fully charge the battery (off vehicle).

Before doing that, if you can jump-start the vehicle, check the battery charging voltage, which should be 13 – 14 Volts. You could also measure the battery charging current with the current clamp. If the battery was flat, this should be in excess of 10A with the engine revving at 1,500 and over.

After fully charging the battery, measure the ‘everything off’ battery drain current, which should be less than 0.1A. Restart the vehicle with the fully charged battery, to test its ability to crank the engine, fully charged.

Leave the vehicle overnight, then try to restart – if it starts OK, I would suspect that you did not have adequate charge in the battery (as stated above). If the battery cannot crank the engine, then you might have a second, intermittent drain path.
This will be more difficult to track down, but if you have a secure location for the vehicle (garage), then after parking, leave the hood up – and check the battery drain at regular intervals in order to trace the fault (as with the tow pack).

 

It could be this simple.Does the hood light in the engine compartment go out when closed?
Another test.Put a test light between the pos. thermal and the battery.With the ing off there should be no light(no draw) if there is start pulling fuses till the light goes out and you have found the system causing the problem and find the problem.Some things I have done this test on have had a dim light because of the altanator.sound like you will have bright light and have fun trouble shooting.

 

Try disconnecting the alternator (all wires) and test your drain. If you have a bad diode in the alternator diode pack it will drain the battery and still show a charge with the motor running. A good multimeter has a provision to measure AC in the presence of DC. If it shows any AC in the output with the motor running, you have a bad diode.

 

I have the same problem with my 1998 JGC (UK). It isn't the alternator, battery or door lights at fault. Everything was checked and double checked. I even disconnected the radio to see if that was the cause of the problem. It wasn't ... next morning the battery was flat.

I then fitted a battery isolator


Fit it to the positive battery terminal. Just turn the **** anti-clockwise to switch off/isolate the power..which of course means having to disconnect and reconnect frequently... It works of course. No more jump-starting your vehicle .. just lifting the bonnet/hood 10 times a day when you park/set off somewhere..

I then took it to an auto electrician who found an 0.8 current drain from 'somewhere' in the dashboard instruments or in the circuit board which controls everything. He wasn't able to specify which- circuit board or one of the instruments.

To trace and repair the fault means removing circuit board and instrument pod and sending it away to a specialist, which wouldn't be cheap...

The auto electrician fitted a small switch on the steering column. It simply switches off all power to the circuit board/instruments. Switch it of when the vehicle is parked and the battery doesn't discharge. Switch it on and start the vehicle in the usual way..

Usually my Jeep battery would discharge within 4 hours. The switch worked fine for two days until I reconnected the radio. The battery again discharges so I presume there were/are two faults: One being the circuit board/instruments .. which the bypass switch fitted by the auto electrician worked, and secondly the radio, which was disconnected when I went to the auto electrician's.

I'll ask the auto electrician to look at the radio in due course - but these guys don't come cheap. What I intend doing is buying a couple of meters of heavy duty battery cable and a 'kill switch'. I'll reroute the positive cable into the vehicle and fit the kill switch somewhere. I'll be able to 'disconnect/reconnect' the battery from inside the vehicle which will be more convenient.



Battery on/off ..isolator.. kill switch. Probably the easiest and cheapest option. Fit it somewhere convenient inside the vehicle

It just means that each time I switch on and start the Jeep I'll have to punch in the radio code. Mine is 2255 .. if you need a radio code try it .. who knows ..?

A simple cure is best - a kill switch inside the vehicle. Don't become too bogged down recharging batteries and looking for elusive electrical faults

 

I've seen these isolator switches on heavy construction equipment, usually in a lock box. I've also seen fuel shut-off valves on custom cars to prevent theft. The only problem I can see is the PCM will lose it's stored memory, which shouldn't be a big deal.

Like the man said, check the voltage with the jeep running. It should be around 13.5 to 13.75 when the alternator is putting out. A fully charged battery should show around 12.6 volts. There is a good You-tube video on how to do an ignition off draw test. You'll have to search for it because I don't have the link.

 

Same problem but another thread suggested that the key in their 98 GC can be removed one click past the off position in the ACC on position.

Sure enough, checked mine and found the batt drain was due to the key switch being left in ACC and then being removed. Key shouldn't come out there but it does. I screwed a small metal bracket to stop the key switch from going to ACC on. Problem solved.

 

As a Minister I have little hate for anyone, but I would like to once again reiterate how much I hate Automotive Engineers...These kind of things are why.

 

I had a similar problem with my 97 ZJ. The Infinity Gold amplifier under the back seat wasn't turning off completely. Simple fix, remove the amplifier.