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Discussion Starter #1
Hello to all on this beautiful day in SC,
My 2004 Ram 2500 has been "ailing" with a non-working passenger front headlight for some time. I replaced the bulb, and it did not solve it, but after an hour of pounding my head, it mysteriously began to work. Two months later it goes out again. I then began searching and read about the front control module. I did not pursue hard, because after a day or so my light began to work again. Now, after a month or so of working, it is off again and has been for a week. I need to fix this thing.
My current thinking is that the FCM may not be the issue since the light has "repaired" itself twice. Maybe just a wire issue, or ground issue somewhere. Can someone help me determine how to tell where to look to determine the source of the issue? The truck is in great condition, with little or no corrosion anywhere; hard to believe it could be a ground issue, but certainly worth investigating.

Thank you in advance for the advice.
David in SC
 

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If you have already checked the various bulb connections, you can also try a "hard reset" of the trucks many control modules by unplugging both battery grounds for at least 15 minutes....

Removing the power from them forces the modules to reset to factory software parameters which sometimes fixes issue like this if they are a module problem and not a wiring problem.
 

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Discussion Starter #4
Well, i may be out of ideas. Thank you all for the inputs; they are helpful. I am no electrical engineer, but i do own a voltmeter....and i once slept in a Holiday Inn FWIW. Here is what i did tonight:
1) Verified continuity to ground on the center terminal of the pigtail connector with the power to lights off - Perfect and identical on both driver and passenger side.
2) Verified power to both other slots in the pigtail connector (presumably high and low beam) with light switch off. Pass side(bad side) - 11.6V to both. Driver side (works fine) had 11.5V to both. Not sure why there is 11.6V when switch is off. Seems to me with good ground and voltage the bulb should be on even with switch off? Turned switch on and volts drop to 11.5 on both high and low beam and down to 11.4V on driver side. I did not check to see if ground continuity was interrupted when i turned switch on; should i have?
3) Tried another bulb in passenger bad side. No response with switch on or off.
4) Wiggled all connectors and harness all the way from headlight to the FCM - not even a flicker as my daughter watched intently.
5) Disconnected both battery grounds for 30 minutes. No impact.

I suppose i might should have tested some of the above with the truck running?

This really makes no sense to me. I can't get by why there is 11.6V at the pigtail with the lights off. But i remember that being the case last time i dug into this, and the lights all the sudden fixed themselves.

Any more thoughts?

Thank you for the help
David in SC
 

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IIRC, and contrary to common sense, ground is SWITCHED on these trucks.

Did you try to force "hard" reset by disconnecting the batteries yet??
 

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Discussion Starter #7
Hello All,
I decided tonight to read voltage on the hi and low prongs to the center prong; presumably the ground, versus reading ground at the battery -. Well, same exact reading on both driver and passenger side. I did it with switch on/switch off/hi and low beams....always about 11.5 volts on both outside prongs. So, ground being switch controlled may make sense, and i just do not know how to use my voltmeter. That is entirely possible.
After scratching my head for a while, i tried the not-so-obvious, and switched sides with the bulbs. I knew they were both good; almost new, and they go out like clockwork about one month after the one year warranty is up. Voila, both headlights now work.

I have no clue what i did - really nothing. This frustrates me even more, and i am sure i will be back at some point. How long remains to be seen. In the meantime, we have lights!

Thank you kindly for all the help you have offered.

David in SC
 

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The headlamp connector would be my concern try to clean the surfaces and adjust the prongs/tabs to make a tighter fit for the headlamp prongs/tabs.
Been some time since I had mine open don't recall the exact contact configuration.
 

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Discussion Starter #9
Thank you tryNto. You may be on to something. I went out to venture to work this AM and light is out again. I will follow your lead and check surfaces and prongs/tabs first thing when i get home.

Thank you very much,
David in SC
 

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Thank you tryNto. You may be on to something. I went out to venture to work this AM and light is out again. I will follow your lead and check surfaces and prongs/tabs first thing when i get home.

Thank you very much,
David in SC
Check each pin (whether it's male or female) carefully in the connector. I just recently had an issue where my high beams were not working. I could not figure out for the life of me what was going on, I tried swapping bulbs, ballasts (I'm running a projector retrofit), checked all of my wiring and connections. On the harness, the high beam prong had pushed back in the connector housing causing it not to make connection with the applicable pin. It must have got strained when I was moving things around during my timing gear housing fix. Pushed the pin back up in its slot, made sure that it clicked into place, all was good after that.
 

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^^ (y) that's what I was talking about.
 

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Discussion Starter #12
Well, i got my butt kicked again tonight. Thought i was onto something when i began my efforts tonight and my amber park light was also out. I lightly tapped the main headlight assembly and the amber came on. Ah hah. Took both bulbs out, cleaned all connections and verified they were snug and in place. They look very nice; no corrosion. I again verified bulb against two other good ones. Also changed the amber with a new one just to be safe and it works great. No luck though on the low beam. Hi beam works great, but no low. i wiggled all connections, and even smacked a few; nothing. Not even a flicker on low beam and the amber did not go out again. Sure seems like a loose connection, but wiggling, pushing, and pulling should yield some kind of change.

Any other thoughts? I don't have a pin puller to remove pins from plug. But, hey it reads 11.5V anyway. Why would i suspect it to be bad when it looks almost new?

About to cave in and call for help. This is very frustrating.

Thank you all for your help,
David in SC
 

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Headlight switch sends signal to cluster , which then sends to FCM/PDC gives power.
Easiest perform cluster test, help rule out check if good communications, good switch/good FCM/PDC ??
If that checks out, then with test light verify power, voltage meter can erroneously show volts but no amps .
Should not have any test light illumination with headlight switch off. If you do short some where take proper ohm readings of circuit wiring should be about the same.;)
 

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Discussion Starter #14
Thank you rghavana. I wish i was coming back with positive feedback, but no luck. I went back at it this morning; this time with a test light. I first removed both headlights. Verified both read identical with a voltmeter. Both empty receptacles still read 11.5-11.6V to ground with switch off. With the flickering test light, you are correct, no current with switch off. When low beam switch is turned on, both driver and passenger low receptacle pins light the plug. When turned to hi beam, both driver and passenger high beams light the plug. I did this test grounding to the center pin of the receptacle, and also direct to battery ground...no change. I even connected 3 test leads to the bad (passenger) side female pins with the other ends connected direct to the bulb prongs - no different; it does not light up on low beam, but does on high beam. I did this thinking maybe there was a bad connection, although all pins are nice and shiny.
After swapping the bulbs to verify the known good would not work in the passenger receptacle, i then wired the bulb direct to the battery positive and ground to verify both high beam and low beam work, and they do. When plugged into the headlight receptacle, only high works.
This is the craziest thing i have seen, and it has me totally baffled. I enlisted the help of my engineer wife to see if she saw something i didn't. After doing initial tests, she made me step away versus taking my word for it when i told her the bulb was not burning. She did not believe me, as she saw all the tests and witnessed that both driver and passenger are identical. She also saw both driver and pass read exactly the same in every aspect...with the exception of the passenger (bad) side being 0.1 volt higher than working driver side....11.6 versus 11.5

I then took the FCM off just because i had not previously done that. I had read of possible grounding issues causing headlight issues, but my mounting bolts go direct to the plastic casing, so no potential for ground issues there. I did pull the unit to verify all pins were clean and intact; and they are.

I told wifey i might just have to go visit a dealer. Oh yeah, i also pulled codes, and there are none.. I may not sleep if i have to go visit a dealer. Get out the pocketbooks.

I did not check headlight switch as you suggest, but may soon. For now, i will just use fog lights. This is crazy. Any and all thoughts are very much appreciated.

David in SC
 

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check EMIC (cluster codes)?? its free and easy a communication issue between headlight switch and cluster and IPM can cause issues.
ACTUATOR TEST
The instrument cluster actuator test will put the instrument cluster into its self-diagnostic mode. In this mode the instrument cluster can perform a self-diagnostic test that will confirm that the instrument cluster circuitry, the gauges, and the indicators are capable of operating as designed. During the actuator test the instrument cluster circuitry will
position each of the gauge needles at various calibration points, illuminate all of the segments in the Vacuum Fluorescent Display (VFD) units, turn all of the indicators on and off again, display any Diagnostic Trouble Code (DTC)
information, and display the number of ignition key cycles that have occurred since the DTC was detected. It is suggested that a note pad and pencil be used to write down any fault information that is displayed during the test for reference.

Successful completion of the actuator test will confirm that the instrument cluster is operational. However, there may still be a problem with the PCI data bus, the Powertrain Control Module (PCM), the Engine Control Module (ECM), the Front Control Module (FCM), the Transmission Control Module (TCM), the Transfer Case Control Module
(TCCM), the Airbag Control Module (ACM), the Controller Anti-lock Brake (CAB), or the hard wired inputs to one of these electronic control modules. Use a diagnostic scan tool to diagnose these components. Refer to the appropriate diagnostic information.
1. Begin the test with the ignition switch in the Off position.
2. Depress the odometer/trip odometer switch button.
3. While still holding the odometer/trip odometer switch button depressed, turn the ignition switch to the On position, but do not start the engine.
4. Release the odometer/trip odometer switch button.
5. The instrument cluster will simultaneously begin to illuminate all of the operational segments in both VFD units and perform a bulb check of each operational LED indicator. The VFD segments and LED indicators remain illuminated as each gauge needle is swept to several calibration points and back. If a VFD segment or an LED indicator fails to illuminate, or if a gauge needle fails to sweep through the calibration points and back during thistest, the instrument cluster must be replaced. Following these tests, the actuator test will proceed as described in Step 6.
6. The text “C Code” is displayed in the odometer VFD for about three seconds. If there is no stored fault information, the display will show two pairs of zeroes in the format “00” “00”, which indicate that the display of fault
information is done. If there is stored fault information, two sets of two-digit alpha and alpha-numeric fault codes will appear in the odometer display for a three second interval. The first pair of digits represents a Diagnostic
Trouble Code (DTC), or fault code for the instrument cluster. The second pair of digits is a counter for the number of ignition key cycles that have occurred since the displayed DTC was set. The instrument cluster will continue to display additional sets of two pairs of digits at three second intervals until all of the stored codes have been displayed, which is again signaled by a code of “00” “00”.
 

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Discussion Starter #16
Thank you so much Rghavana. You are so kind to share that much information. I will work through it as i am able. In the meantime, i am still totally baffled as to how the headlight plug shows voltage and current, and still will not light up the low beam filament. Heck, if it is as easy as disassembling the plug and swapping the hi beam and low beam wires, will that work? I never use high beams anyway, and they work fine on both sides. This just makes absolutely no sense to me.

I am also thinking about maybe just temporarily direct-wiring the low beam wire to the battery and through a toggle switch in the cab. I hate driving with a HL burnt out. To me, it gives the impression i just dont care, and that is far from the truth. I spent 4 nights on this last week, and am afraid if i spend one more unsuccessful night, i might have to break out a ball bat - jk!.

Is this a good time to convert over to projectors, or some other upgrade, or do they all receive power and signals the same way? I am not averse to putting money in my 320,000 mile truck; just don't want it to be at a dealership.

Thank you again for all the help.
David in SC
 

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Thank you so much Rghavana. You are so kind to share that much information. I will work through it as i am able. In the meantime, i am still totally baffled as to how the headlight plug shows voltage and current, and still will not light up the low beam filament. Heck, if it is as easy as disassembling the plug and swapping the hi beam and low beam wires, will that work? I never use high beams anyway, and they work fine on both sides. This just makes absolutely no sense to me.

I am also thinking about maybe just temporarily direct-wiring the low beam wire to the battery and through a toggle switch in the cab. I hate driving with a HL burnt out. To me, it gives the impression i just dont care, and that is far from the truth. I spent 4 nights on this last week, and am afraid if i spend one more unsuccessful night, i might have to break out a ball bat - jk!.

Is this a good time to convert over to projectors, or some other upgrade, or do they all receive power and signals the same way? I am not averse to putting money in my 320,000 mile truck; just don't want it to be at a dealership.

Thank you again for all the help.
David in SC
There are multiple ways to run HID's in projectors (yes, if you get HID's, put them in projectors please), but as long as you have good hi and lo signal from at least 1 side of the vehicle, you can run a bi-xenon harness or similar off one side's signal.

If you go that route a bit more is involved in tricking the computer to think it's running halogen bulbs, which means you'll need resistors between the vehicle harness and the relay (whichever side you control the harness from) as well as inline with the opposite connector that you don't end up using to power the relay.
 

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Takes 5 seconds to perform EMIC cluster test , will help pin point where issue could be, rule out FCM and EMIC modules.
post results for info.
The problem with bypassing issue is, if issue being caused by something,ie short in wiring, that can damage other components, I would want to know.
 

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Discussion Starter #19
Thank you to all. I definitely want to know what is causing my dilemma; just need to wait until the weekend to do the tests. Just for kicks, i went by the local dealer yesterday to inquire about them hooking up - minimum charge was $120. I passed and told them i would continue my investigations.
Thanks for the offers - i still have work to do.

David in SC
 

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Discussion Starter #20
Hope everyone is enjoying a nice Easter Sunday!

I finally got back to this today; nice to have daylight savings time and not need lights. I have no trouble codes. All lights illuminate; all gauges calibrate, and i get two sets of 00 00. That is good news.
I will now proceed with the fuse panel and FCM diagnostics as best i can.

Thank you for the continued help.
David in SC
 
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