97 HD 250 dim headlights
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Tuned
Joined: Aug 2009
Posts: 274
Likes: 4
From: British Columbia
97 HD 250 dim headlights
Th headlights on my 97 HD are really dim. Daytime running lights same way, and the high beam indicator quit as well.
Any suggestions, Im thinking maybe daytime running lights module.
Any suggestions, Im thinking maybe daytime running lights module.
Fleet Mechanic
Joined: Jan 2023
Posts: 1,281
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The problem could be anything from the battery to a bad ground or wiring.
Here are the wiring diagrams. DRL sends low power to high beams. It should not affect the low beams. Take some voltage measurements at the battery and headlights.
https://lemon-manuals.la/Ford/1997/E...unning%20Lamp/
Here are the wiring diagrams. DRL sends low power to high beams. It should not affect the low beams. Take some voltage measurements at the battery and headlights.
https://lemon-manuals.la/Ford/1997/E...unning%20Lamp/
PLATINUM SPONSOR
Joined: Feb 2026
Posts: 90
Likes: 12
Good points above—I'd also start with checking grounds and voltage at the headlights. On older trucks, even a small voltage drop or corroded connector can make DRLs and low beams look very dim. If wiring checks out, it’s also worth looking at the headlight lenses themselves since haze can reduce output a lot.
Hotshot
Joined: Jul 2020
Posts: 10,268
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From: Near Salt Lake City
I would be finding the ground locations in a 1997 EVTM for the headlights
A visual inspection of the harness at the headlight switch to see if it's melted
And a visual inspection of the TS switch connectors to verify they are plugged in all the way
How bright are the lamps when you pull the T/S stalk back for "flash to pass"?
A visual inspection of the harness at the headlight switch to see if it's melted
And a visual inspection of the TS switch connectors to verify they are plugged in all the way
How bright are the lamps when you pull the T/S stalk back for "flash to pass"?
Cargo Master
Joined: Mar 2007
Posts: 2,757
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Take a volt meter and measure the voltage drop on the power side of the bulb, then the ground side. The bulb must be plugged in to do this test.
Once you see which side [power or ground] is bad, then you can proceed. Otherwise, you will be wasting a lot of time.
Once you see which side [power or ground] is bad, then you can proceed. Otherwise, you will be wasting a lot of time.
Fleet Owner
Joined: Jul 2006
Posts: 20,322
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From: Mi'kma'ki
LED bulbs are cheaper than that relay kit now. No longer a need to do that. Sometimes bulbs just get very dim due to age too, don't forget. I had a car that you couldn't hardly see anything, horrible yellow and dim. Put a new set of bulbs in it, just some halogens and it was like a new car again. It's far less common than when they just blow, but I assure you, it happens.
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Lead Driver
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LED bulbs are cheaper than that relay kit now. No longer a need to do that. Sometimes bulbs just get very dim due to age too, don't forget. I had a car that you couldn't hardly see anything, horrible yellow and dim. Put a new set of bulbs in it, just some halogens and it was like a new car again. It's far less common than when they just blow, but I assure you, it happens.
Yes halogen dimming is by their nature , they get old and the halogen effect inside the bulb becomes less effective over time if i remember right because deposits from the filament reacting with the bulbs atmosphere and leaving deposits on the glass or something?
ANyway, if you DO go LED. Realize that you must use an LED with a heat sink braid instead of a fan, because of how the bulb is retained into the housing.
Cargo Master
Joined: Mar 2007
Posts: 2,757
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I purchased Phillips LED bulbs and they use a fan. No problems after 2-3 years of use. Granted, I tend not to drive at night, but when I do, they work.....very well. Not certain why you think you must use the heat sink type bulbs, when you don't have to.
Fleet Mechanic
Joined: Jan 2023
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But let's stay focused on the OP's problem.
Fleet Mechanic
Joined: Jan 2023
Posts: 1,281
Likes: 434
Cargo Master
Joined: Mar 2007
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If indeed there is a voltage drop [which there probably is and a simple test would prove] fixing the problem is better than putting in a part that consumes less power. An LED certainly could fix the dim issue, but the real problem is probably still there. This would apply to relays too. Relays consume much less current than LED's which could fix the OP's concern, but not really fix the real problem. Sometimes, people just want an outcome and quick.
I've been waiting on the bench for years about LED's since most technologies take a few years to work to my expectations. I waited until a name brand [reliable] company dived into the LED market and after a couple years after that, I purchased my bulbs. Again, so far so good. Having spare bulbs [brake/headlight] is just a good idea no matter what technology you have. Buying good quality parts tends to bring better long term results.
I've been waiting on the bench for years about LED's since most technologies take a few years to work to my expectations. I waited until a name brand [reliable] company dived into the LED market and after a couple years after that, I purchased my bulbs. Again, so far so good. Having spare bulbs [brake/headlight] is just a good idea no matter what technology you have. Buying good quality parts tends to bring better long term results.
Lead Driver
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can you show me how big the fan is? the two types i tried with fan were too large to fit with the retainer ring