If you have a Dodge Ram 2500 or 3500 pickup truck and are struggling with a low beam headlight that won’t work on one side, this post will help save you from a costly trip to the dealer to troubleshoot and replace your TIPM (Totally Integrated Power Module).
First, let me explain what I’m talking about and allow me to vent for just a moment…
How To Troubleshoot Faulty
2006 Dodge Ram Low Beam Headlight
After replacing the driver’s side headlight bulb twice on our 2006 Dodge Ram 2500 SLT 4WD Cummins Diesel pickup, the low beam still wasn’t working. I swapped the known good bulb from the other side and the low beam was still out, even though the high beam and fog lights were all functional. I started researching other causes for the issue and discovered that 2006 and later model year Dodge trucks have no fuses nor relays controlling power to the lights. When you turn on the headlights, the wires to the low beams return a signal to the ECM (Engine Control Module) which sends power to the lamps.
Really? What brilliant engineer decided to remove an inexpensive relay from the circuit, requiring replacement of an $800± computer instead of a $20 bulb? Perhaps the goal was to drive more DIY repairs back to the dealership. But I digress…
How does the IPM control power to lights? The smarter question is why!
Technically speaking, the “smart” technology of the TIPM monitors current of the lighting circuits. Should amperage fall outside the preset normal operating range, a fault signal is sent to the module. Apparently, after a certain number of power cycles the circuit will be permanently disabled by the computer until it is reset or replaced. Unfortunately, resetting only works for a short period and that is if the issue is caught in time. But of course, the first step anyone is going to take when a headlight goes out will be to replace the bulb. Other steps might include tracking down loose wires, testing the switch, or replacing a fuse or relay — if there was one!
With so much discussion about the Dodge Ram low beam headlight issue however, chances are the cause is a computer module failure. Don’t just take my word for it though, check out these forums I found filled with reports of failing lights and recommended troubleshooting that explain the issue in much greater detail:
Save Yourself from Expensive Dodge Dealer IPM Replacement for Low Beam Headlamp Repair
Now, how exactly does one fix this $800± issue for about ten bucks in parts? First, let me state that I am not a certified technician, nor do I accept any liability for damage resulting from the following procedure. I am happy, however, to share what worked for me and saved me about $775 and only took about an hour to complete.
The credit for this cheap fix actually goes to Rene, for correctly answering the Dodge mechanic at the dealership who asked her if her husband was handy with electronics. Her affirmative answer resulted in him saying, “then he can do this,” handing her a simple sketch illustrating what needed to be done, and telling her there was no need to make a service appointment. The service manager didn’t care much for that.
It’s quite simple really, so I will quickly explain and then provide a couple tips to consider:
Jump the low beam power lead from the opposite side.
That’s it! To make the job harder on yourself, here are the 2006 Dodge Ram Front Lighting Wiring Diagrams. If you are so inclined, have at it. The only challenge I encountered was tracking down the correct wires at the wiring harness. The mechanic’s note read, “Jump the white and tan wire in black box to the white and green wire in blue box.”
By “boxes” I figured he meant the wiring harness plugs in the engine compartment. I easily found and confirmed the white and tan wire from the right headlight leading into the black box. The white and green wire in the blue box, however, did not test positive for continuity from the left headlight. This was either a wire to something else, or it may have indicated a break in the wire somewhere between the wiring harness and the lamp. Either way, the fix I describe below solved the problem. If you can correctly identify the two low beam wires in the gang plugs pictured above, this job will be much easier and take even less time.
Always more comfortable being safe than sorry, I didn’t want to jump the wrong wires and cause a short making matters even worse. So I connected a jump directly between the two lamp sockets and routed the wire safely along the frame under the front grill. First, I tested the mechanic’s theory by splicing into the wire on the “bad” side and just plugging it into the socket on the other. Use a meter to identify which hole powers the low beam, in my case it was on the right with the retaining clip on top.
Once I confirmed that both low beams lit up after splicing into the power from the other side, I routed the jump wire along the frame to the other side, securing it with zip-ties. At each end I tucked the new wire into the plastic wire harness tubing and left enough slack at each end for easy replacement of the bulbs. The only thing that might have made my job easier would have been some snap on splice connectors.
Do Not Trust Your Meter
Prior to reading this or the forum discussions I provided links to above, one might be inclined to just test voltage to the low beams on each side as part of the troubleshooting procedure when trying to fix a Dodge Ram truck with a headlight out on one side. Doing so will likely just have you scratching your head like I did when I discovered both wires were getting the exact same power.
If you’re experiencing headlight problems like I describe, go ahead and troubleshoot your bad low beam all you want. Or, if you have a thousand bucks to burn, take your truck to the dealership and let them do it. If you catch it early enough, they may be able to flash the ROM in the computer and clear the fault most likely causing the trouble, for a while.
Which is safer, high beams or low?
As an interesting aside, this issue did spur a discussion about whether it’s better to drive around with one headlight or both your high-beams all the time. Sure, it’s frustrating to have people keep flashing their brights back at you, but is a cop more likely to pull you over for a headlight out or failure to dim your lights? What do you think?