C5 under hood lamp voltage drop
Thread Starter
Heel & Toe
Joined: Jun 2023
Posts: 20
Likes: 1
From: Beautiful Delta BC.
C5 under hood lamp voltage drop
Hi everyone, hope you all are doing great. A new problem for me that I have researched and just can’t get the necessary info I need. My underhood lamp if fluctuating with its brightness. I have tested the #2 fuse and everything on that fuse is working great except the hood lamp. After measuring the battery voltage I find I have a 1.6 voltage drop at the frame connector to hood lamp by the headlamp assembly. When I run jumper wires to the lamp wiring everything is perfect. I tested the ground at the lamp wiring connector right to the battery neg and it was perfect. I am assuming that there is a connector someplace where the fuse supplied power to the lamp circuit but dammed if I can find it. Has anyone dealt with a connector that has the wiring for the lamp that can guide me ? Any help appreciated. !
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Thread Starter
Heel & Toe
Joined: Jun 2023
Posts: 20
Likes: 1
From: Beautiful Delta BC.
The mercury switch works perfectly. It’s the voltage drop I am interested in after it turns on , sometimes turns on bright sometimes very dim. I am pretty sure I am missing something, as this car is new to me so lots to learn.
Thread Starter
Heel & Toe
Joined: Jun 2023
Posts: 20
Likes: 1
From: Beautiful Delta BC.
The actual drop is at the rad area connection to the lamp, totally removing the switch from the circuit. I am a bit lost as I am not familiar with how the wiring runs on this car and where connections might be and if they are coverned by something I am not aware of. It’s a very small issue, but I do have the time now to fix it. Thanks for your input.
Pro
Joined: Aug 2010
Posts: 622
Likes: 169
From: Montgomery Texas
At first glance, the circuit looks pretty straight forward. Power flows from the passenger compartment fuse box relay #37 to Fuse #2.
From the passenger compartment fuse box fuse #2, it flows through the under hood fuse box.
It enters into the under hood fuse box via connector C2.
And, it exits the under hood fuse box via connector C3.
From C3 it flows to connector C113.
From C113 it flows to the lamp.
From the lamp it flows to ground splice SP100.
SP100 is grounded at ground point G102, which is on top of the frame rail, near the passenger side headlamp.
An intermittent problem suggests a loose, or wet/corroded connection somewhere in this circuit. All things being equal, the engine compartment is a more inhospitable environment than the passenger compartment. Keep in mind, however, that water ingress near the passenger compartment fuse box, due to clogged udders is a common concern. That said, if your problem was caused by water ingress into the passenger compartment, one would tend to expect a whole host of symptoms, rather than just the under hood lamp being affected.
Good luck!
From the passenger compartment fuse box fuse #2, it flows through the under hood fuse box.
It enters into the under hood fuse box via connector C2.
And, it exits the under hood fuse box via connector C3.
From C3 it flows to connector C113.
From C113 it flows to the lamp.
From the lamp it flows to ground splice SP100.
SP100 is grounded at ground point G102, which is on top of the frame rail, near the passenger side headlamp.
An intermittent problem suggests a loose, or wet/corroded connection somewhere in this circuit. All things being equal, the engine compartment is a more inhospitable environment than the passenger compartment. Keep in mind, however, that water ingress near the passenger compartment fuse box, due to clogged udders is a common concern. That said, if your problem was caused by water ingress into the passenger compartment, one would tend to expect a whole host of symptoms, rather than just the under hood lamp being affected.
Good luck!
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From: Cape Coral, Florida
Thread Starter
Heel & Toe
Joined: Jun 2023
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From: Beautiful Delta BC.
When I check a ground circuit , I test the resistance looking for something unusual and I do that to the frame and to the battery to look for any differences. I also use a test light and a multimeter. My ground to the lamp is 100%, I definitely have a loss of voltage, while testing from the battery ground with both the test light and multimeter at the connector right before the lamp. Tron Z gave me a great path to check and will do it when I have time. Thank you for your reply !
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,626
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From: Cape Coral, Florida
When I check a ground circuit , I test the resistance looking for something unusual and I do that to the frame and to the battery to look for any differences. I also use a test light and a multimeter. My ground to the lamp is 100%, I definitely have a loss of voltage, while testing from the battery ground with both the test light and multimeter at the connector right before the lamp. Tron Z gave me a great path to check and will do it when I have time. Thank you for your reply !
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From: Charlotte, NC (formerly Endicott, NY)
Hi everyone, hope you all are doing great. A new problem for me that I have researched and just can’t get the necessary info I need. My underhood lamp if fluctuating with its brightness. I have tested the #2 fuse and everything on that fuse is working great except the hood lamp. After measuring the battery voltage I find I have a 1.6 voltage drop at the frame connector to hood lamp by the headlamp assembly. When I run jumper wires to the lamp wiring everything is perfect. I tested the ground at the lamp wiring connector right to the battery neg and it was perfect. I am assuming that there is a connector someplace where the fuse supplied power to the lamp circuit but dammed if I can find it. Has anyone dealt with a connector that has the wiring for the lamp that can guide me ? Any help appreciated. !
Bill
Thread Starter
Heel & Toe
Joined: Jun 2023
Posts: 20
Likes: 1
From: Beautiful Delta BC.
When I had my 97 that light was a constant irritant. Either the bulb was broken due to the hood closing hard or the contacts on the bulb didn't make a good connection to the contacts in the bulb housing. Check the bulb to make sure one or both of the ends aren't coming loose from the bulb (some bulbs have metal caps on the ends, check the hood mounting point contacts to see if they are corroded or dirty, and check to see how well the bulb fits into the mount's contacts. After the car's B2B warranty expired I removed the bulb and never worried about the light again. I don't remember whether my 03Z had an underhood light or not but my C6Z didn't and the C7Z I have now doesn't have one either.
Bill
Bill
Thread Starter
Heel & Toe
Joined: Jun 2023
Posts: 20
Likes: 1
From: Beautiful Delta BC.