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03 with SKIM, no start

sierradmax

TJ Enthusiast
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RI
A friend of mine has an 03 Sahara and told me it wasn't starting. Trying to diagnose over the phone was a challenge but it pretty much stemmed from a battery change. I made my way over and performed some basics.

Jeep will not start nor will it turn over. I can hear fuel pump turn on and SOME relays energize in the the PDC.

Battery was reading 12.4V
No loose wiring
Battery ground to starter block ohm'd out.
Battery positive to starter positive ohm'd out.
No voltage to starter signal wire at the ignition terminal when ignition placed in "start" position.
Jumped starter and engine turned over.

Fuse in PDC is good.
swapped starter relay with another (Horn) and same result.
Bypassed neutral safety switch.. Nothing.

I pulled the starter relay and looked at the wiring schematic of the relay.

With ignition in the "On" position, I probed terminal 30 in the PDC and got 12V. With ignition off, 0 volts. This must be the battery common feed to the starter signal. I did the same to terminals 85 & 86 when the ignition was in the "Start" position, assuming this would energize the coil and relay a signal to the starter. Didn't see any voltage across either terminal.

Looking at the vehicles wiring schematic for the starting system, is it time to start tracing wiring back to the ignition? I asked him if he was rough when replacing the battery and possibly damaged wiring/connections to the PCM. The vehicle does have SKIM. I'm not familiar with how it works but the key light flashes several times (then goes off) with ignition on.

61a+PSZLmfL._AC_SX522_.jpg
 

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mrblaine

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Quail Valley, CA
A friend of mine has an 03 Sahara and told me it wasn't starting. Trying to diagnose over the phone was a challenge but it pretty much stemmed from a battery change. I made my way over and performed some basics.
Sounds like someone hooked it up backwards, figured out the mistake, fixed it and now it has problems.
Jeep will not start nor will it turn over. I can hear fuel pump turn on and SOME relays energize in the the PDC.


The vehicle does have SKIM. I'm not familiar with how it works but the key light flashes several times (then goes off) with ignition on.
The flashing light indicates that SKIM was functional and working correctly at some point and now is not.

To help with the rest, when the SKIM is working correctly, the rig will start, run for a few seconds while the SKIM module checks the SKIM key and tells the PCM that all is good or not. If good, it stays running. If not good as in the SKIM key has not been used to start it and something like a screwdriver in the jacked ignition has been used, then it will shut the motor down.

To add some insult to your friend's injury, if they tried to start it enough times without a functioning SKIM that was working, then they likely bricked the PCM. You need to find out if it did start and run for the 2-3 seconds and then finally stopped and now it won't do anything.
 
OP
sierradmax

sierradmax

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Jan 1, 2020
Messages
892
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RI
The flashing light indicates that SKIM was functional and working correctly at some point and now is not.

To help with the rest, when the SKIM is working correctly, the rig will start, run for a few seconds while the SKIM module checks the SKIM key and tells the PCM that all is good or not. If good, it stays running. If not good as in the SKIM key has not been used to start it and something like a screwdriver in the jacked ignition has been used, then it will shut the motor down.

To add some insult to your friend's injury, if they tried to start it enough times without a functioning SKIM that was working, then they likely bricked the PCM. You need to find out if it did start and run for the 2-3 seconds and then finally stopped and now it won't do anything.

Is the flashing light (only for a couple seconds) a light function test at startup or should it not flash at all with a good SKIM key? The flashing light does go off (disappear) after a couple seconds.
 
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mrblaine

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Is the flashing light (only for a couple seconds) a light function test at startup or should it not flash at all with a good SKIM key? The flashing light does go off (disappear) after a couple seconds.
The flashing light is telling you that the SKIM system was working correctly and now it has a fault.
 

Irun

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Oct 31, 2019
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Virginia
Unsure. All I know is I had a no start issue once when I accidentally severed the wires there, after cleaning and painting the battery tray. I fixed the wiring and it started. It's possible there was another issue, but it only happened that one time.
 

mrblaine

Crew Member
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Nov 20, 2015
Messages
22,959
Location
Quail Valley, CA
Unsure. All I know is I had a no start issue once when I accidentally severed the wires there, after cleaning and painting the battery tray. I fixed the wiring and it started. It's possible there was another issue, but it only happened that one time.
Not hard to tell. Just unplug it and see if it starts.
 

NOTNSUV

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Sep 18, 2021
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Spring Creek, NV
@sierradmax i can disable skim if you would like to send it into me.
Good to know.

Freaked out a bit today learning more about the SKIM, like multiple attempts kills it and that if I misplaced my SKIM key somewhere remote I'm screwed, and that the 'spare' keys I have are only good for unlocking doors.

Called my local dealer and scheduled for a second SKIM key to be programmed. Gonna cost $200 but beats the alternative. They tell me only Chrysler and their techs have access to the PIN (mine is unknown and the owner's manual was purchased after I bought the LJ so no notes in there). They also have modules available for the '06 @ $300+ (who knows for how long) so I'd considered whether to buy one or if SKIM was something that could be removed. Something to ponder. I know it's theft deterrent but getting stranded is not an option.

Good stuff here as always.
 
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