Gauge Lights not working - 1997 Defender 130

[GTJR]

I have a 1997 Defender 130 and am trying to track down a problem with the Gauge/Speedo lighting.  All other lights are working well interior and exterior.  I started by simply trying to replace the bulb...no luck.  Am thinking some other sort of ground/earthing problem.  Was trying to track down the header joint....I believe C287-1/C287-5 but it's located behind the lower dash if my information is correct.  Before I go down that path wanted to know if there are some other things I should checkout.....I haven't done lots of electrical, but can follow instructions.  Thanks in advance for any advice.

[Snagger]

Firstly, make sure the bulb is getting power.  There is no point in stripping and rebuilding the earth if the feed has disconnected.  The earth does cause problems often enough to be a suspect, though.

[GTJR]

Thanks.  Again, i am new to the electronic side.  What is the best way to test power at the bulb socket....  I have voltmeter....sorry for what to most is a basic question.  I did try to find using the search function.  Thanks.

[steve b]

Is there a switch for turning the dash lights off for parking with sidelights only?

...worth checking as the instrument back lighting is more than one bulb so if all are off..? 

Steve 

[FridgeFreezer]

A multimeter or voltmeter is fine for checking if there's power to the bulb sockets - the dash illumination is on a red wire with a white tracer if memory serves (not to be confused with white/red which is the starter motor solenoid), and the gauges are grounded with black wires.

While you're in there, decent LED replacement bulbs (CoB type) are a worthy upgrade.

[GTJR]

16 minutes ago, steve b said:

Is there a switch for turning the dash lights off for parking with sidelights only?

...worth checking as the instrument back lighting is more than one bulb so if all are off..? 

Steve 

No switch.  They come on with the headlight switch.....in theory.  No separate switch.

[GTJR]

21 minutes ago, FridgeFreezer said:

A multimeter or voltmeter is fine for checking if there's power to the bulb sockets - the dash illumination is on a red wire with a white tracer if memory serves (not to be confused with white/red which is the starter motor solenoid), and the gauges are grounded with black wires.

While you're in there, decent LED replacement bulbs (CoB type) are a worthy upgrade.

Ok....yes you are correct on the colors.  I did check the socket with the voltmeter - Light switch on.  I also checked the fuse and it is fine - also other items on that fuse (16) are working.  Not sure what to check next to trace this down.  Thanks for all your help!

[Peaklander]

Here's the back of my gauges on a 96 110. You can see that each bulb holder has the +12V on the red/white and the 0V is on the black.

You already said that you can read +12V on the red-white and to do this I assume you are holding the other voltmeter probe onto metal somewhere, to provide the 0V (chassis) connection.

Switch on your lights and then put your voltmeter across those two connections into the bulb. I doubt you will see 12V because it sounds as though the black wires are not connected to earth. If this is so, then get a length of cable and touch it from that black terminal at the back of a bulb and onto the same metal that you used for the voltmeter probe. Assuming that the bulb then lights, that will prove that you have a missing 0V at the gauges.

[FridgeFreezer]

If you've got 12v and a shiny new bulb and the holder isn't damaged, I'd use the multimeter on continuity mode (buzz) and check there's continuity from the ground wire to actual ground.

[GTJR]

Just to be clear.  The only thing I have checked is the actual socket.  And there was no power by touching both leads to the red and black wire.  I will try both the items listed by @Peaklander and @FridgeFreezer tomorrow.  See what I can find out.  Thanks.

[Snagger]

With the lights switched on, you should get 12v at the terminals of the red wires with white traces.  The black wires should read zero with lights on or off.  However, just because you’re getting power to the end of the wire and visible, crimped part of the terminal in the bulb holder, it isn’t necessarily the case that the power is getting to the bulb itself - there could be a fault withholder or bulb, such as an overheat causing the plastic to soften and allow the terminals to move away from the bulb contacts.   Or just a blown bulb…

It seems odd to have more than one failed, but if poor quality or over-bright bulbs had been fitted, that could cause excessive heat in the holder contacts and melting of the plastic.  That tends to be common on Defender front sidelights, after all.  LEDs would be a reasonable option to prevent this reoccurring, if that does transpire to be the fault - they should have both far greater longevity and much lower temperature than filament bulbs.
 

 

[GTJR]

Here is what I did.  I put the red probe into the back of the bulb and ran the black probe to the ground on the battery under the drivers seat - Lights on and key on - headlights are working.  No voltage reading on my voltmeter.  

I am assuming this might rule out that the issue is exclusively the earth/Ground - I had a known operating ground on the battery?  In addition I was able to connect my voltmeter from the black wire on the socket to the ground on the battery.  It indicated continuity...

So I am thinking no power to the to these sockets.  If you agree - what now?

Thanks again for helping

[Peaklander]

If you are correctly using the voltmeter then yes, no power.

Here's the circuit diagram - yours won't be far off this.

 

There are some other connections - the clock and the cigar lighter. Do these light-up? If they do then the fuse is OK and you have a problem where the power moves onto the red/white.

If not I would find the fuse and be sure that it is intact and making good contact in the fuse holder. I think you should verify that you have power on the RO (red / orange) from the fuse.

[GTJR]

@PeaklanderThanks.  I will work to track that down today.  Yes my clock is working and the lighter - no light on the clock tho.  What is the split in the power line at A121/a122 - how do you find the location of those points / and Sj2 - are they listed somewhere?  Thanks so much!  

[Snagger]

With all of those lights out, you’ll have a common fault.  My bet is on the wiring connection from the light switch or a bad fuse/ fuse holder.

[Peaklander]

There's a common point on the +12V feed and the other at the 0V post but finding the +12V would be easier I think.

Don't look for that splice connector yet; identify the correct fuse and make sure that the RO cable has +12V. The splice will be harder to find in the back of the dash.

You really need to be sure you are looking at the correct circuit for your vehicle. Here is a link to a late 300 and they are interactive, in that you can hover and click a connector reference and maybe find out more.

https://www.lrworkshop.com/wiring-diagram/defender-1997-300tdi/interior-illumination

However identify the RO cable at the point where it leaves the fusebox.

I am a bit slow with this feedback as I have managed to catch Covid for the first time and I can hardly manage to type; in-spite of four jabs!

Edit: you could simply pull each fuse, check each carefully for continuity as it isn't always obvious if one has blown. Also look at the brightness of the conductors and then refit the fuse - maybe with a spot of petroleum jelly on the contact surfaces.  

Edited December 22, 2022 by Peaklander

[Peaklander]

Just for good measure, this is the back of the fusebox. You should be able to carefully move it forward to allow a bit of RO searching. Disconnect the battery though to avoid nasty sparks.

https://www.lrworkshop.com/wiring-looms/defender-1995-300tdi/bulkhead-loom-300tdi-rhd/bulkhead-300tdi-rhd-fuse-box

This a screen shot of it

[steve b]

1 hour ago, Peaklander said:

Just for good measure, this is the back of the fusebox. You should be able to carefully move it forward to allow a bit of RO searching. Disconnect the battery though to avoid nasty sparks.

https://www.lrworkshop.com/wiring-looms/defender-1995-300tdi/bulkhead-loom-300tdi-rhd/bulkhead-300tdi-rhd-fuse-box

This a screen shot of it

Hope you feel better soon peaklander

Are you sure it's red/orange? later Lucas colour standard is red/white for RH sidelights and panel back lights.

Red/orange is rear fog switch supply.

I think the supply and earth wiring for the dash instrument backlighting is a small plug in loom? I might be wrong of course but checking for any connections behind the dash panel is worthwhile. I also can't find a ref to a separate fuse for the panel lights on 300 fuseboard layouts?

Steering wheel off and unplug the speedo cable and the two main dash multiplugs will allow the panel to move enough to make access easier. 

Steve

[FridgeFreezer]

On 12/20/2022 at 7:36 PM, Peaklander said:

You already said that you can read +12V on the red-white and to do this I assume you are holding the other voltmeter probe onto metal somewhere, to provide the 0V (chassis) connection.

@Peaklander I think the Covid is going to your noggin - OP never said he had 12v on the socket (your post threw me off!).

@GTJR I would trace the red/white wire back towards the light switch per Peaklander's diagram, checking for 12v along the way. The junction C223-5/C332-5 into the lighting loom would be my #1 suspect given all the gauge lights are out but the actual lights are on. Removing the fusebox unnecessarily is a bit of a faff and risks creating new faults!

[Peaklander]

Ok I’ll back off but on my diagram the feed from the fuse is RO. It doesn’t split to RW until further down to the gauges and he says that the clock doesn’t light up. 

[steve b]

6 minutes ago, Peaklander said:

Ok I’ll back off but on my diagram the feed from the fuse is RO. It doesn’t split to RW until further down to the gauges and he says that the clock doesn’t light up. 

No need to back off at all, I'm just going from memory stripping a 300 wiring loom off the bulkhead for rebuild and what I found with a quick web search.

What fuse number is it you refer to?

Steve

[Peaklander]

On 12/20/2022 at 3:47 PM, GTJR said:

I also checked the fuse and it is fine - also other items on that fuse (16) are working.

 

12 hours ago, GTJR said:

no light on the clock tho.

According to the circuit diagram I posted, the OP is at the correct fuse but as you can see, these two bits of diagnosis ‘conflict’.

[GTJR]

Back at it tomorrow.  I will track some of these posts.  See what I can find then update.  Thanks again for all the help. 

[GTJR]

Found the problem!  Tested connection Red Orange into the c332-5 connection / no power to feed RW C223-5.  So went back to the fuse box.  I thought I had first checked it - Fuse number 16.  turns out i was checking a 5 amp fuse in the top row - (dumb)....there was no fuse in slot 16 and the fuse holder was melted there!   So the question now is what to do.  

For the short term, do I need to replace the fuse box or can I start by putting a 5amp in line fuse connected to the RO wire?  At least to see if it blows.....or do you recommend something else? @Peaklander@FridgeFreezer @steve b @Snagger

I am a bit confused by the fact that other things powered by fuse 16 seem to be working - (but I am very novice at these repairs);

• Trailer pick-up - Not verified - IMG_0079.heicIMG_0079.heicIMG_0079.heic
• RH front side lamp - Working - when turn signal on....
• instrument pack - all instrument lighting seems to be working -  
• dim dip relay - dim dip works....
• cigar lighter - Yes - but not red glowing
• in-line resistor - not verified
• Illumination - coolant temperature gauge, speedometer, fuel gauge, clock - NOT Working

IMG_0079.heic

Thanks again for your help!  Its been amazing!

GT

PS. Get well soon! @Peaklander

[steve b]

The cigarette lighter is fuse no.9 (main feed - back light is part of fuse 16)

Fuse no.16 should be just rh sidelights and dash instrument back lighting. A resistance check from the RW(or RO) output side of fuse 16 to earth with good bulbs fitted to all back lighting. It should show resistance, low or zero is a fault to ground. 

Changing the meter to amps and making the connection to the fuse socket with the two probes with sidelights on will confirm amp load before putting a fuse back in. 

Is that C322-5 a crimped connection or a plug? just out of interest.

Steve