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Post by jamesge on Mar 30, 2011 18:20:59 GMT -6
Does anyone have headlight wiring diagram for 2001 4.0?
My low beam headlights wont come on. I can hear the relay clicking under the hood when I turn the switch. Fuses are fine, and yes the bulbs are fine.
I have power to the relays but no power to the bulb connectors.
Anyone know what is between the relays and the connectors?
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Post by nelson480 on Mar 30, 2011 20:13:40 GMT -6
Check your ground?
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Post by maxheadroom on Mar 30, 2011 21:19:16 GMT -6
The HDLP LOBM relay switches to two 15a fuses, one for each lamp. The grounds for each lamp are separate. Measure the voltage on the top of each fuse to ground to make sure you have power when the relay is one. You can measure the voltage with the fuse in as each have a small metal tab on top of the fuse you can put a pointed meter probe on. From each fuse, both lamp circuits are completely separate.
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Post by jamesge on Mar 31, 2011 4:02:34 GMT -6
No power to the fuses....
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Post by maxheadroom on Mar 31, 2011 9:17:52 GMT -6
If there is no power on either fuse, then it could be the relay, it may be picking up but the contacts are burnt. If you swap a relay and it still does not work, then pull the relay and check with a resistance meter between the #30 relay socket pin and both fuses. you should have continuity or 0 ohms. If OK check for 12v to gnd on the 87 pin, it should be hot at all times. This should pin it down. Max.
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Post by oldwino on Mar 31, 2011 11:37:24 GMT -6
Here's the diagram max is talking about. Hope it helps. Good Luck.
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Post by jamesge on Mar 31, 2011 19:46:43 GMT -6
Thanks guys. My ohmeter isnt working, but I was able to test for 12V coming to the relay. With key in "off" position, there is constant 12V supply on 87. When key is in "on" position, and headlight switch turned to "on" position, there is also 12V supply on 85...
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Post by maxheadroom on Apr 1, 2011 8:34:07 GMT -6
The relay switches 12v to relay pin 30, so you should have continuity from 30 to the top of the fuses, if you don't then you have an open circuit between the two. Jumper the pins between 30 & 87 the lamps should light. Max.
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Post by jamesge on Apr 1, 2011 14:56:14 GMT -6
This is going to problem be simple fix...
I have 12 volts going to the low beam bulb socket; however, I plug in the bulb and neither will work. I noticed when I plug in the bulbs, my 12V now goes to zero.
Is this a bad ground? If so, I have been trying to jumper a new ground to the frame and I still get now light.
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Post by oldwino on Apr 1, 2011 17:02:56 GMT -6
This is going to problem be simple fix... I have 12 volts going to the low beam bulb socket; however, I plug in the bulb and neither will work. I noticed when I plug in the bulbs, my 12V now goes to zero. Is this a bad ground? If so, I have been trying to jumper a new ground to the frame and I still get now light. This is NOT a ground issue. What you have is a high resistance connection somewhere between your power source and the bulb. I have seen this before on my Intrigue with one of the cornering lamps. Had voltage when measured with a meter, but it would not turn on the bulb. Turned out the MFS had bad contacts in it and they replaced it under warranty. Don't know if you have any electrical background, but what's occurring is when you check with a meter( high resistance input with almost 0 current draw) you read voltage because you're not drawing enough current to drop voltage across the bad connection. Once the bulb is in the circuit the amount of current it draws results in the voltage drop across the bad connection and resulting in no voltage at the bulb. What you need to do is with the bulb in and the lights on, start checking for voltage at the bulb and work your way back toward the power source until you get good voltage. Your bad connection will be there or the next connection point (connector, fuse, relay) downstrean toward the bulb. My bet is a bad relay with burnt contacts, a connector with corroded pins, possibly a bad fuse(even though it looks good and checks good with a meter) or loose fuse or relay clips in the fuseblock. Since the relay is common to both lamps......good place to start.
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Post by jamesge on Apr 1, 2011 18:50:23 GMT -6
Thank you for the help! Much appreciated.
Here is what I just did to test the circuit: I made a wiring harness that bypasses the factory harness but used only passenger side 9006 connector as the switch source to power both low beams. It worked for a second. With everything powered, I touched the low beam relay and it made spark noises. After that, it didnt work. I swapped the relay with another (fuse as well) and it was a no-go. So, Im assuming something is amiss in the fuse box terminals?
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Post by oldwino on Apr 1, 2011 19:34:13 GMT -6
When you said you "touched" the low beam relay, do you mean that you kind of moved it a little in its socket with everything on and you got sparking noise from it? Any sparking is not good and the most likely location of your problem. Disconnect the battery and check the fuseblock for bad solder joints or broken wires would be my next suggestion.
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Post by jamesge on Apr 1, 2011 20:13:13 GMT -6
Yes, when I touched the relay, it had the spark noise. Then the lows quit working.
Whats the easiest way to remove the fuse block?
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Post by maxheadroom on Apr 1, 2011 22:33:05 GMT -6
What I would do is pull the relay and jumper from relay socket pin 87 to 30 this will eliminate any relay problem. If is still has no effect jumper from 87 to the top of the fuses, both lamps are independent from the fuses on, so it if neither lamp is working, then it is between the relay block and the fuses. The whole relay block will lift up if the bolts are removed, but there is not alot of room to work in. max.
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Post by jamesge on Apr 2, 2011 15:41:02 GMT -6
Max,
Thanks for the help. Its fixed. When I jumpered 87 to the fuse, they worked. So I noticed that pin 87 into the fuse box was wore. I took and bent pin 87 on the relay to give it more contact point. Now it works. Not sure how to permanently fix but maybe the bending of the relay pin will make it permanent.
I guess Occams Razor needs to be payed attention to further.
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BNICOV
Aurora Lover
Posts: 782
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Post by BNICOV on Apr 5, 2011 6:34:03 GMT -6
That's one I haven't heard in a while. The easiest solution to a problem is usually the right one.
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Post by raywwatchz71 on May 30, 2021 8:38:29 GMT -6
I found this thread 10 years old now and I have the same problem. All my lights work except the low beams. I switched the hi beam relay with the low beam relay and still have no power to the low beam sockets. Someone posted a wiring diagram to this thread 10 years ago but it doesn't come up now. Any chance that someone can put that diagram back up again. Thanks in advance for any help.
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Paulaurora
Super Moderator
Posts: 3,823
Staff Member
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Post by Paulaurora on May 30, 2021 11:14:03 GMT -6
hope it helps . click to enlarge.
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Post by raywwatchz71 on May 31, 2021 17:21:10 GMT -6
Thanks, it can't hurt.
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Post by raywwatchz71 on Jun 2, 2021 7:51:24 GMT -6
I'm back and stumped I've followed wires checked fuses and relays and taken the headlamp housing completely out. I'm getting 12 volts to the low beam pins and when I plug in the connector with no bulb I get 12 volts. as soon as I plug in a lowbeam bulb the voltage drops to zero. I'm using the standard 9006 bulb and I checked with an ohm meter the bulb is good. Any Ideas out there?
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RCA1186
Administrator
Rob
Go Pack Go!
Posts: 4,835
Staff Member
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Post by RCA1186 on Jun 3, 2021 6:22:08 GMT -6
Both sides are inoperative or just one side?
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Paulaurora
Super Moderator
Posts: 3,823
Staff Member
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Post by Paulaurora on Jun 4, 2021 14:21:27 GMT -6
ground to the fuse box?
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