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Strange information for my 08 G.C. limited 5.7 hemi V8. A few weeks ago my radio / C.D. player was operating intermittently. It would switch to G.P.S. with no warning. One morning the radio would not operate at all. No sound, panel lights,C.D. door, nothing. I thought a fuse was blown. Next day the vehicle would not turn over at start, just the click click of a starter motor not engaging. After a jump and reading from AAA a new battery was installed. Every thing back to normal. Full starting cranking and best of all radio back to normal. Moral to the story: no radio indicates battery issues. p.s. dealer wanted to change out radio to which I found a second opinion.
 

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Well with our WK's when the battery goes bad everythign starts getting funky not necessarily the radio. Alot of people have all crazy dash light going on and off.
 

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Well with our WK's when the battery goes bad everythign starts getting funky not necessarily the radio. Alot of people have all crazy dash light going on and off.
X2. It's because everything goes through the PCM, even starter motor control. Just replaced OEM factory battery after 5.5 yrs of service (garage-kept). It started to go down quickly and I experienced REN MyGig radio issues and ATC heater blower intermittent operation at startup. [The blower motor is controller by a circuit module, not a resistor.]

New battery = normal operation. :thumbsup: Anyone with an '08 on its factory battery probably should be shopping for one right now. Got my DieHard Gold (Group 94R) on line with store pickup (no shipping $$) on sale with $20 off normal price. I did that because I've never had an issue with DieHard batteries and used them in every car I've put a replacement battery in since 1969. No reason for me to change now...........:)

Now, if Sears would only pay me to do a commercial for them....wait, I just did. Never mind, return to your regularly-scheduled programming. :D
 

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amen to the replacement battery after 5 years. My '07 was just fine til ONE DAY...I went to start it & got the dashboard light show and no crank. I put the battery on a trickle charge for 16 hours, tried again - it started (diesel), but no radio, no A/C, no EVIC, and when I turned on the headlights that was all she wrote.

New battery from Batteries Plus (closest to my house) and I'm on the road again
 

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Discussion Starter #5
I had a brand new never used fully charged 665 cold crank amp battery in my garage for emergencies. When I jumped it to my 08 G.Cherokee lights worked, radio and all other dash lights worked. The motor, V8 Hemi cranked o.k. but would not fire the engine. AAA battery installed a new 750 C.C. amp unit and every thing was back to normal. Apparently my jumper battery was over taxed with all the jeep accessories and the starter motor so there was not enough amps to ignite the injectors. Live and learn I guess huh ??:)
 

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The biggest revelation for me was the starter solenoid control / starter motor going through the PCM. IIRC, the PCM will not fire up unless battery voltage is >10.5V.

Voltage is 1 consideration; the 2nd is the capacity. The latter is what usually goes first as the battery sulfates with age. Many check voltage, but few look at capacity as a barometer of battery health. It also takes some who knows what he is doing to properly perform the test & interpret the results.
 

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I suspect to really test a vehicle battery you should test it under load. I'm not sure how to create a load condition on a 12 volt battery, but I suspect a home owner with a good voltometer and some basic knowledge could do it. Any hints ?
 

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I suspect to really test a vehicle battery you should test it under load. I'm not sure how to create a load condition on a 12 volt battery, but I suspect a home owner with a good voltometer and some basic knowledge could do it. Any hints ?
I don't think you can effectively do it without some serious research and equipment assembly.

Sears has always done it for FREE for me. Ask for a BATTERY CAPACITY TEST. Their "toy" is fairly foolproof (connects a load resistor inside the device)....hooks up to battery like a charger or jumper cables. Readout will tell you acceptability of battery state.

There are 2 things I always do when the battery capacity test is performed:
1. Charge your existing battery fully before you go. Check terminal voltage with engine stopped and with engine running (charging).
2. Read the results of the Battery Capacity Test yourself. Just had an inexperienced salesman try tell me what the capacity test results were and was shielding the ouput screen from my view. Trust, but verify.........
 
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