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Discussion Starter · #1 ·
Hi All,

I'm new to actually posting on the forum but have lurked a little when issues have come up. I'm at my wits end on this one right now and wasn't able to find a write up on testing or replacing the ignition switch, which I think may be my issue.
Here's the scoop, I have a 2011 JKU, 6 speed manual, chipped, cold air intake and throttle body spacer, otherwise stock with respect to anything that I could imagine affecting it starting. Right now when I turn the key to the starting position I get one click in the fuse box from the K2 ("run") relay. Nothing from the starter relay. I checked voltage at the starter, it's good on the big pole from the battery but wasn't getting anything on the smaller wire that goes to the blade connector. Jumping 12V from the battery to that blade connector does activate the starter and the motor turns over freely, but won't start even with the key in the "on" position. I've tried it with the clutch pushed in, and tried the clutch switch bypass, connecting the yellow and red wire from that to ground even to fool it, as well as trying to start in 4LO which I had read makes the clutch irrelevant.
Is there something else I'm missing that could be wrong? So far as I can tell the ignition switch is working OK, it acts like normal in both the ACC and ON positions. Help!

Thanks!
 

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If it helps I had a bad wire going to my starter back in the spring. Caused all sorts of headaches until the shop located it
 

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Discussion Starter · #3 ·
Thanks NJ, I'm starting to think that I may have been overthinking it and got ahead of myself. Guessing that it's probably actually just the starter solenoid trigger wire. Since jumping that straight to the battery makes the motor turn over, and since it doesn't get any voltage when I turn the key (even though the starter relay clicks and seems ok), it must be shorting out, right? It's dark out and my driveway is dirt and big pokey rocks, so I'm having a hell of a time trying to trace the wire. Can someone let me know how the wire is routed and how I might go about swapping it out?
 

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Which starter relay are you talking about? Is it the one in the TIPM aka "K3"? Just making sure you aren't talking about the solenoid. You won't get any power going to the smaller wire to the starter solenoid (that is on the starter motor) without the K3 relay activating.

To troubleshoot this you need to know a little bit about the starting system. First, the ignition key and switch is not directly connected to the starter motor. The TIPM has final control of the starter solenoid. When you turn the key to start, you are telling a few modules that you want the motor to start.

It works like this. The ignition switch has 12v coming in and will apply 12v in start (and run and acc) to both the TIPM and to the Wireless Control Module (WCM). The ignition switch has another wire that come out of it and goes to the WCM. It will send a different voltage to the WCM depending of the key is in, key is ACC, key is on RUN, key is on START. This voltage varies from like .5v to 4.5v depending on the key position. The WCM then can determine key position and it sends a message over to the TIPM over the CAN BUS as to what the key position is (ACC, RUN, START, etc).

Once the TIPM has the 12v from ignition switch and the proper start message from the WCM, it starts the starter motor by activating the relay starter which sends 12v to the starter solenoid. Which then turns the starter and Engine.

The best way to start testing this is to plug a scanner in to the Jeep and view live data for the TIPM and the WCM. JSCAN can do this at low price point. You can find the data PIDs in the TIPM for the 12v and for the key position. This will tell you if your ignition switch and WCM is operating properly and then you can focus on the TIPM and it's relays.

If you don't have a scanner, I'd look at that K3 relay. There are ways to test that relay or the socket the relay sits in but that will be another post if necessary. It won't tell you everything but may help break the system into small sections to test.

Also some other things to check that may be easy that are part of this starting system:
- K4 relay. This is the run/start relay and provides power to the ECM in Start and shares control power with K3.
- M33 fuse. This is the fuse for power to the PCM when in start
- M27 fuse. Power to the ignition switch
- F13 fuse. Power to the WCM
- M13 fuse. Power to the WCM

Hope that helps...let us know what you find.
- M28 Fuse. Power to the PCM
 
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