OEM – Issue with front only running / turn signals – both sides. The front running / turn signal lights turn off when turning on the head lights on my 2009 Jeep Wrangler Sahara. With headlights on and using the turn signal the dashboard turn signal cadence is faster as it would to indicate a bulb out. Turn off the headlights and the running and turn signals in the front work per design with a normal dashboard turn indicator cadence. The rear running / break / turn signals lights continue to work regardless of the head light operational state. The only recent electrical repair was replacing the AC switch harness. Could this recent work be related to this front turn signal issue. How do I begin to trouble-shoot this?
Technical Service Bulletin on turn signals
There might be a couple different ways to approach this issue. First off, I did look to see if there were any TSB’s on the turn signal issue but did not find any.
So moving on through the repair manual I noticed several Body codes related to the turn signals. You will need to have access to a scan tool on order to pull the body codes as they are different from the check engine light codes. Once you have the codes post them in the comments below and we can dig deeper.
Front Turn Signal Theory of Operation
Let me start by saying I had no idea that the engineers had figured out a way to over complicate turn signals. But they have. Lets dive in with how it operates.
The Totally Integrated Power Module (TIPM) receives a bus message requesting turn signal lamp illumination. When this bus message is received, the TIPM provides a pulsed voltage output through the front turn signal control circuit. The front turn signal control circuit connects to the dual filament Park and Turn Signal Lamp. The same ground circuit is used for both the Park and Turn Signal filaments in a dual filament lamp.
Turn Signal Switch
There is a chance that you have some kind of wiring issue. I will provide the wiring diagram for the turn signals below. Potential loose ground connection/s are also possible. Wiring harness brittle or cracking may be a cause.
So with all that I would like to let you know that the most common cause for turn signal related issues is caused by a multi-function switch failure. I went ahead and looked up the part for a 2009 Jeep Wrangler in case you want to give it a go.
Purchase Multi-Function Switch – Verified Fit: 2009 Jeep Wrangler
Turn Signal Wiring Diagram
