t.g0r · 2024-11-26T08:33:08+0000

Hi,

I’m come into a problem whilst upgrading to LED headlights on my 89 110. Whilst the switch is off and the keys out of the ignition one of the headlights remains on very dim (as seen in the picture).

I have worked out there is a constant 8v to the headlight plug on the dip beam live. When the halogen headlights were installed they were functioning correctly.

Is this a problem with the relays for the headlights? I’m absolutely stumped and am fed up with taking the fuses out every time I park the car.

Any suggestions are much appreciated

lynall · 2024-11-26T08:35:16+0000

I think early cars had no relay, and all the power went through the light switch on the column?

t.g0r · 2024-11-26T08:43:52+0000

lynall said:
I think early cars had no relay, and all the power went through the light switch on the column?

I’m struggling to find the proper wiring diagram for the car. From my understanding there are two separate relays one for each headlight that does the dipped and main beam. With the power going through the column like you say.

t.g0r · 2024-11-26T09:12:15+0000

Bit of an update. After taking things apart and the relay out for the headlights the light still stays on. Leading to believe I have a short somewhere

boguing · 2024-11-26T11:09:13+0000

That or a bad earth on something that's permanently live. The favourite place for this is behind the instruments - too much wire in there for the space available.

Hicap phill · 2024-11-26T11:18:35+0000

t.g0r said:
I’m struggling to find the proper wiring diagram for the car. From my understanding there are two separate relays one for each headlight that does the dipped and main beam. With the power going through the column like you say.

Have you got a modified headlight loom?
These have 2 relays

Remove fuses for the head lights & see if they are still on.

8v on the live shows also a problem.. should be 12

t.g0r · 2024-11-26T14:22:56+0000

Hicap phill said:
Have you got a modified headlight loom?
These have 2 relays

Remove fuses for the head lights & see if they are still on.

8v on the live shows also a problem.. should be 12

Hi, removed the fuses and the light goes off, what was the 8v reading turns into a 12v reading on pin 87 of the relay when I do so. The 8v is the constant feed to the light even when the truck is off and the key is out of the ignition, which is my problem. Can this be a short or a bad ground somewhere? Sorry electronics isn’t my strong point by any means

When the headlights are on properly they are 10.8v

I have, from my understanding, standard wiring due to only having one 5 pin relay for the headlights

Hicap phill · 2024-11-26T15:25:12+0000

Where is this headlight relay?
Have you changed the relay to see if that’s at fault?

Did the led headlights come with any resistors or 1 way diodes?

t.g0r · 2024-11-26T16:14:46+0000

Hicap phill said:
Where is this headlight relay?
Have you changed the relay to see if that’s at fault?

Did the led headlights come with any resistors or 1 way diodes?

I’ve not changed the relay yet. It seems as if that it’s not at fault due to the power being there without the relay present. The relay is a single relay behind the fuse panel above the trans tunnel at the bottom of the bulk head.

Unfortunately no diodes or resistors supplied. I believe if it had a resistor in the circuit it would solve the issue. However Im under the impression that would be a patch and not fixing it at the cause.

Using one halogen headlight and one led headlight they both are off correctly so it could well be I just need a resistor

Hicap phill · 2024-11-26T18:25:34+0000

t.g0r said:
I’ve not changed the relay yet. It seems as if that it’s not at fault due to the power being there without the relay present. The relay is a single relay behind the fuse panel above the trans tunnel at the bottom of the bulk head.

Unfortunately no diodes or resistors supplied. I believe if it had a resistor in the circuit it would solve the issue. However Im under the impression that would be a patch and not fixing it at the cause.

Using one halogen headlight and one led headlight they both are off correctly so it could well be I just need a resistor

Or a one way diode to stop the flow of electric feeding back.

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