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jjohns29 01-15-2010 10:30 PM

2004 Jeep Grand Cherokee starting problems
I'm stumped on a starting issue I have with a 2004 Jeep Grand Cherokee Laredo. I've been away quite a bit lately with work and it started fine and worked great 8 weeks ago but when I returned it won't turn over or even show power to vehicle. Took out the battery, checked the charge and it was fine then I reconnected the battery and the lights, panels, clock etc all worked great. I then tried to start the engine again and after the split second I turned the key it acted as if it shorted out and all the panels, lights, etc went dead again. If I unconnect then reconnect the battery it will do the same until the second I turn the ignition. Anybody got any ideas before I pay to have this thing towed in?

Billy_Bob 01-16-2010 09:07 AM

How did you check the charge of the battery?

I use a multimeter set to DC volts 20. A fully charged battery will read 12.65 volts.

Modern vehicles have things which are always using a little electricity like the engine computer and radio. Over time this will slowly drain the battery.

How to use a multimeter...

If the battery does not have a full charge, buy a battery charger at an auto parts store and charge the battery over night. Or jump start the vehicle and let it run a while to charge the battery.

Bondo 01-16-2010 09:24 AM

Ayuh,... Clean the battery terminals,+ the other ends of the batteries wires...
It sounds like a Corrosion problem...

jjohns29 01-16-2010 10:19 AM

I tried jump starting it with no luck, same experience. Battery shows full charge with the meter I've got. One of the terminals did have corrosion on it but I cleaned it off with a steal brush. I felt fairly confident that I cleaned all the posts and terminals pretty good, but will check once again. Thanks for the advice.

Billy_Bob 01-16-2010 10:36 AM

Ok, jump starting and checking the battery with a multimeter is good. You have confirmed that there is enough power there to start the vehicle and that is not the problem (always check these things first)...

Next is to check the starter with a multimeter to be sure it is getting power. If it is getting power at the solenoid (starter relay) when the key is turned, and at the main power terminals, then this would be a bad starter.

If it is not getting power at the main cables, check those cables.

If it is not getting power at the solenoid, check all fuses. If not that, get a factory service manual set including electrical diagrams manual (order from dealer) and troubleshoot the circuit following the troubleshooting instructions.

How to test fuses...

How to use a multimeter...

ihildreth 01-16-2010 07:31 PM

If you disconnect and reconnect the battery, all of the car electronics work correct? But when you turn they key it all goes out and doesn't come back on? It seems to "short out" when you turn the key? These are classic symptoms of a badly discharged or bad battery. I suggest removing the battery from the vehicle and taking it to a parts store for a load test. Autozone, Advanced Auto, NAPA, O'Reillys, etc normally offer this service for free. You may find you have a battery that is more discharged than you think, or a bad cell.

Most cars don't have a lot of excess capacity in their charging system, if your dead car has a bad cell in the battery it is possible that you'll never be able to get the thing started via jumper cables. You're unable to jump start the car with another vehicle? What was the vehicle you were using? How long did you have the two cars connected before you attempted to start?

Yoyizit 01-16-2010 07:51 PM


Originally Posted by jjohns29 (Post 383705)
it won't turn over or even show power to vehicle.

The cranking circuit is the battery, cables, connections, solenoid and starter motor.

It sounds like a bad ground connection [shared by other electrical components] in the series circuit mentioned above, but confirm that the battery voltage at the posts stays at 12v during attempted cranking.

You're looking for a connection or cable that has several volts across it during your attempt to crank the engine, instead of just millivolts. This connection may be OK for lighter loads and may get hot during attempted cranking. During normal cranking the heavy cables may have 1/4v drop along them due to the 200A or so used for cranking.

Let's say the rest of the car draws 1A, so it's a 12 ohm load. If the ground connection goes to >>12 ohms during heavy current draw then the rest of the car sees much less than 12v, so it doesn't work.

Measuring the voltage at the cigarette lighter socket during cranking will tell how much voltage is missing; i.e., if you measure 3v then there are 9v being dropped across a connection somewhere.

If you can post an online link to a wiring diagram [not schematic] for your vehicle, troubleshooting should be easy. The wiring diagram will show connections shared by other components, a schematic just shows 'ground.'

It's possible that there are only one or two connection points/cables that can cause this symptom.

ihildreth 01-16-2010 10:08 PM


Originally Posted by Yoyizit (Post 384193)
It sounds like a bad ground connection [shared by other electrical components] in the series circuit mentioned above, but confirm that the battery voltage at the posts stays at 12v during attempted cranking.

Normally the only shared ground between the starter and the rest of the car is where the negative battery cable attaches to the chassis. The starter grounds to the engine block, which is grounded to the rest of the car. Check that connection for corrosion.

I still vote for bad/discharged battery. I know every car I have every tried to start with a mostly dead battery has done exactly as the OP describes.

Willi 01-16-2010 10:32 PM

A cheap check would be to drop the starter and take it to an electrical shop. They can test the starter. Could be the bearings or bushings worn and the armature making contact with the body. They could tell you and if it is the case, usually a cheap bearing replacement.

Dieseltech 01-22-2010 12:48 PM

Definately sounds like a bad battery to me....just checking it with a meter will show its current state of voltage but the battery, if showing full voltage (12.6) needs to be load tested to acurately ensure that it is adequate for operating the vehicles electrical systems. Most any auto parts store can load test it for you, but it needs to have a full charge or fairly close to be accurate. If it checks out ok...check your ground connection on the battery, loose, corroded, etc....then check the other end of the ground cable to ensure it hasnt corroded or came opinion says more than likely your battery will fail a load test!

Dr Bob 01-22-2010 09:41 PM

Jeep Starting Problems
I have a couple of Jeeps and they both give computer problems. The 1997 Cherokee does not like mobile phone towers. Can take half an hour to unlock or start. Then again if it decides today is not the day the windows will work, then a battery disconect cures the problem. The 2002 Cherokee sometimes decides that the starter won't turn over. Enging fault light comes on. New Battery, and all other systems work. It seems to happen after a 5 minute run. At the serve when filling up with fuel. Or at a friends place. Both sites, road serface on an angle. Heat or fluid levels? If I rake it through the auto change two or three times with the key on it will start? Inhimibitor swich? I am told Jeeps don't have one? Another way I can start it is by taking a lea:(d from the starter fuse to the positive battery terminal. The starter will turn over and with the key turned to the norman starting possition it will start? Dealers can't fix it? Not a good get away car. Any thoughts.

Billy_Bob 01-23-2010 09:12 AM

FYI - If you have a new discussion, click on "New Topic" on the upper left.

As to your Jeep electrical problems, this is an advanced "intermittent" electrical problem. As a rule, most automotive technicians don't have the equipment or expertise to troubleshoot these problems.

Also their repair system is to quickly fix a problem and get the vehicle out the door, not work on a problem over a period of several weeks as could be required with this problem. Or drive it near a cell phone tower and test various circuits with test equipment to learn what is going on.

There are people out there who know electronics inside and out. And there is test equipment which can be connected to various points to "record" what is going on exactly when this happens. This equipment is called a "data logger".

Some areas have "auto electric" businesses and all they do is automotive electrical work. Might have better luck there.

Or you can order the factory "electrical diagrams manual" (part of the factory service manual set - order from dealer) for your vehicle, then perhaps find an electrical engineering student or electrical engineering class at a university who might want to take on this project.

These types of electronics problems are called EMI or ElectroMagnetic Interference.

The solution for this problem is "shielding" using the principles of a "Faraday Cage"...

Dr Bob 01-24-2010 09:53 AM

Hi Billy Bob. Many thanks for your info. Will Try. Regards Dr Bob

Dieseltech 01-25-2010 06:58 AM

Billybob is correct....alot of smaller shops are not tooled to handle this type of an issue, although most decent size dealerships should be capable of diagnosing this issue....but then the problem as Billybob stated is that there could be alot of hours involved in diagnosing it and shops are all about speed of repair...more hours = less money. In my shop we have a gentleman who's sole purpose is this, an hourly employee so he doesnt get screwed out of his pay if it takes a couple days to find the problem, it will also more than likely require a decent scan tool....genysis/pegisys and possible an oscilliscope to capture small intermittent glitches as they happen. I have however in a few cases involving chrysler vehicles (although they were a little older) the VCU (vehicle control unit) and the main harness plug on the firewall have at times gotten water in them and over time corroded allowing voltage to wander were it wants and cause all kinds of problems. The problem with diagnosing this yourself is that it is not always a "take apart and clean" issue, if the corrosion is severe alot of times the small pins will break apart when the connectors are removed and then some terminal replacement is needed with special tools required.... if this has not been checked by anyone maybe mention this, its a quick and easy diagnosis...may take a little time to complete if this is found to be the problem though!

Dr Bob 06-06-2010 06:55 PM

Dr Bob
Hi all happy Jeep owners. Have closed in on the 2004 jeep cranking problem. Wont crank over when filled up at the servo. Well! if I fill it up, leave the cap off, go and pay for the fuel, come back to the car and turn the key to start, Bingo!, it will crank and start. Then we go and put on the fuel cap, close the flap and away we go. Crazy Eh!
What about this! Went to the dealer in Sydney to purchase a thermostat for the 2002 Cherokee. Right, pay for it now, and we will get it in for you.
Get it in? don't you have one? No we get them from the USA. Takes three weeks. Painfull aint it? Don't break down.

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