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I'm trying to figure out why my reverse lights do not work :/
I'm working on a 2002 F250 7.3l Diesel Crew Cab AT if it matters...
What I've tried...
1. Checked Fuse #38 (Trailer Tow and Backup Lamps) -- Checks fine
2. Replaced the bulb on one side
3. Checked Pin 7 on the trailer reverse lights (picture below)-- Tests hot and working.
4. Checked that the truck does not start in reverse -- It does not crank when the selector is in reverse.
I'm a bit stumped... As far as I understand the trailer wiring and the truck wiring are on the same run. I'm going to try the test light on the 'Digital Transmission Range Sensor' shortly to see if I can verify that is functioning.
The previous owner had a backup beeper knifed into the circuit and I would be willing to guess something fried along the way of his shady wiring.
Does anyone know if the reverse lights are on if the truck is not running but the key is on and the selector is in reverse? The reason I ask is for diagnostics so I don't need to actually have a second person to test this out.
Had the same problem a few years back.
Checked out the loom that goes to the trans and found the reverse solenoid sensor to be melted. Cleaned it up and put new female connectors on the wires and BINGO BANGO, had reverse lights... Now, last year, I messed with my 7pin worrying. There's a write back there that's hot when in reverse, but my wires were all crossed up...also, yes, with KOEO, and in reverse, the lights should light up
Yes, IIRC they are on. I would check before and after the beeper was spliced into the harness. Since you're without help, I would set your phone up to record a video and record the back of your truck, then get in with key on, play with the shifter (slowly) . This should tell you if the lights actually work. If you see them go off and on. you'll know they work, but there's an issue with either the shifter (position) or maybe the switch. Hopefully this is clear...
I just jumpered the digital transmission range (DTR) sensor that is on the transmission. Voltage was transmitted to the trailer connector but NOT the reverse lights.
What is this 'reverse sensor solenoid' you speak of? I haven't seen that in any of the wiring diagrams...
As far as the beeper it was only spliced on one side. I was thinking that once upon a time it shorted and smoked the fuse but fuse #38 is my guy right for the reverse lights on the truck?
I just landed +12V on the loom next to the spare tire/rear shock and the bulb lit up. I moved onward to the connector North of the fuel tank and put +12VDC on that. The bulb did not light.
This would lead me to believe that my issue is the loom between the fuel tank and the frame. That area is extremely tight and appears you need to drop the fuel tank to inspect that... Can anyone comment if that's the case?
Several things. IIRC, I thought there were two fuses but if you say your trailer pin reverse light is working but it should not be a fuse. Like I stated earlier I would definitely record or find someone that can watch the truck as you put it in reverse.
Now, regarding the loom if it runs in the drivers frame rail, yes, it is very tight and you probably have to drop the fuel tank. If you know which wire on the backside of the tank I would jump to the front side of the tank and see if you have power there. That should tell you if the damage is between the tank and the frame rail. However if you have power to your trailer reversed, I would think your problem is somewhere else. I don't understand how you could have power up until say right behind the fuel tank and somewhere there's a break in the wire but at the same time you're getting power to your seven pin. Another thing I would change both reverse light bulbs (again), I've had bulbs that were bad even though the filament look good. You may just be chasing your tail right now
FYI, if you end up dropping the fuel tank and have not done it that would be the time for the hutch and harpoon mod also.
Edit: Have you disconnected the plug near the spare tire that connects the harness to the taillights themselves? This is the connection that would allow you install a extra 7 pin in the bed of your truck. I'd look for corrosion and power.
Oh, I think I get you now. So the trailer backup lights work but the actual truck backup lights do not work, correct? I believe if it's a factory install then trailer backup uses an external relay and is separate from truck backup. I'll look at the diagrams for you if this is the case.
Like I said, I would record the back of your truck just to make sure the lights aren't working. They may be coming on but the selectors not actually on (R). However the first thing I would do is change both bulbs regardless of when you change them before. Like I said you might be chasing your tail for no reason and you just have bad bulbs
Like I said, I will record the back of your truck just to make sure the lights aren't working. They may be coming on but the selectors not actually on (R). However the first thing I would do is change both bulbs regardless of when you change them before. Like I said you might be chasing your tail for no reason and you just have bad bulbs
I already confirmed the bulb (at least on one side) is good and working by landing +12V on the black/pink near the rear shock and also by the bulb itself. This should have also confirmed the ground is good.
11-21-2017, 10:04 PM
