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Have to disconnect then reconnect the battery to start

I have a 2003 Jeep Grand Cherokee and randomly it decides not to start unless I disconnect then reconnect the battery. At first when I try to start it every accessory will be off but the A/C recirculation light is on for some reason. When I turn the key all the gauges move sporadically but the engine will not turn over at all, which you can see in the attached video. I disconnect and reconnect the battery and everything works perfectly fine. The only other issue has been that sometimes when I unlock the car (I no longer have keyless entry) the alarm will go off until I start the engine. I have not had both problems at the same time thankfully. Any clues??

I am going to guess it is a bad relay, but that is only a guess. 

Do you have any CELs? (Check Engine Light)

These electronic gremlins are becoming commonplace as computer cars age…Sounds like what is left of your anti-theft/alarm system is malfunctioning and preventing the car from starting…By disconnecting the battery, you are resetting the computer and the alarm and the “no start” condition is removed…You might find the answer on a forum that caters exclusively to Jeep owners…

Yea, sounds like the alarm is stepping in the weeds and pulling the battery gets it back to a known condition.
If it is an after market alarm, you can probably disable it with a hidden switch somewhere - after market alarm installer usually add one, just in case.

Are you sure your battery is good? Some alarms act up when they don’t have 12V on them.

I’ m leaning in the direction of “Caddyman”.

Sound like the immobilizer has been activated. Something to do with your keyless entry not working. Get another key. Fix the keyless entry and see whether that fixes the no starting problem.

I’m thinking you guys are right about the anti-theft problem. I’ll let you know when I find out more thanks for the help!

So I have ask how could the immobilizer could cause the gauges to do what they are doing when the trouble is occurring? I think the gauges are on a different circuit that the ignition is. You might try cleaning the battery connections along with the battery to chassis ground connection to see if that makes any difference.

If the gauges are controlled by a BCM module then there may be a problem with it. By pulling the fuse for the memory power to the module that would reset it and possibly verify the trouble is with it.

So lately it has been extremely difficult to start. By disconnecting and reconnecting the battery it doesn’t work every time but maybe after 5 or so tries. I have been pulling fuse 6 from the junction box which is in line with the security auto shut off. This does not seem to work. Another problem that just came about is sometimes while driving my rpms will go to zero then come back immediately. Also I have experienced very high rpms without giving the engine any gas causing me to travel 20 mph in drive without pressing the pedal. There is oil leaking from somewhere above the oil filter and there is also a speed sensor in that area. Is it possible for the oil to have saturated the sensor causing my rpm problem? The pcm is also in line with the speed sensor so could it all be related? I’m at a loss so anything helps. Thanks, Ryan

I also pulled fuse 7 (pcm) and 19 (bcm) but neither let the car start. Then the car randomly started an hour later for some reason that I do not know.

It was the alternator believe it or not.

1 Like

Crank sensor

8 year old thread and the person said their problem was the alternator .