9 replies to this topic

[The Portly Knaresbruffian]

Hi, long time owner, first time poster.

I have an '89 1293 that had the repeated habit of busting dim dip relays. Finally I removed the relay, replacing it with a land rover bypass relay (identical appearance but just the same as a bypass wire) and removed the dimdip resistor.

Now I have side and headlights that work correctly but no interior or hazard lights. Then after about 2 minutes the headlights don't work and I have working interior and hazard lights.

Before I ring an auto electrician or torch it for an insurance job, can anyone suggest the source of the problem?

[weef]

If the system is returned to standard,  that is with the voltage dropper resistor in circuit and a normal dim/dip relay fitted does everything work as expected ?..

When you say the relay is "busted" what do you mean ?.

How long does it take before the system goes into the fault condition ?.

What are the fault conditions. ?.

[The Portly Knaresbruffian]

Hi Weef. A new dim dip relay would work fine for a few days then the front lights would not work (I can just see a dim glow from the filaments) and the blue main beam dash light would come on instead. The relay would never work again and I would buy a new one, only for the above to repeat.

I have a drawer full of not-working relays.

[cal844]

Try a spare stalk?

[GraemeC]

So the relay isn’t the problem and something else is causing it to fail, and probably also causing the issues with the LR replacement.

I’d suspect the switch first and also do a good check of all earths.

[weef]

The dim/dip relay has 7 connections.

Green switched 12v to relay

Brown/Orange dropper resistor feed to relay.

Blue  main light switch when on Headlight position 12v, headlight Off  0v.

Red/Blue  12v feed when main lighting switch is in the sidelight position.

Brown/Blue  dipbeam/mainbeam switch when in the DIP position feed.

Blue/Red   output to headlights.

Black  earth. USE THIS CONNECTION WHEN CARRYING OUT CHECKS.

 

Check using a multimeter on volts range, ign OFF, main light switch OFF, dip/main beam switch any position there should be NO voltage on any relay connection.

Only switch the ign switch ON   12v on the green and whatever the dim supply voltage , 5v ?, brown/orange and the blue/red and NO voltage on any other connection

Only main light switch in the side light on position 12v on the red/blue, dont really understand what this does ? and NO voltage on any other connection.

Only main light switch in the head light position  12v on blue. 12v on the red/blue relay connection and with the dip/main beam switch on the DIP position 12v on the blue/brown and blue/red relay connection  0v in the main beam position and NO voltage on any other connection.

Ign switch on and Mainlight switch on conditions as the last test with the addition of 12v on the green and 5v on the brown/orange.

 

This is my understanding of how the system works, but from your description of the fault the relay maybe constantly energised and over time burns out. Check for any spurious voltages on the relay connections and ensure that the dropper resistor is on the feed side of the relay not the lamp output side. The fact that the main beam warning light illuminates in the fault condition it maybe the dip/main beam switch is at fault. No wires other than the earth connection should go directly to earth.

[The Portly Knaresbruffian]

Fantastic, thanks all (particularly Weef!) I'll give that a try.

[GraemeC]

That doesn’t sound the correct operation to me:

There should be NO output with just IGN on

12v to sidelights ONLY with IGN off and light switch in first position  

12v to sidelights and 5v(?) to headlamp dip beams with IGN on + light switch in first position

0v to sidelights and 12v to headlamp dip beams with IGN on + light switch in second position

[The Portly Knaresbruffian]

POST SCRIPT

After a couple of days with a multimeter and no luck, I finally tracked down the problem to appalling wiring bodges on the front headlight looms. Dozens of poor splices, loose crimp terminals and insulation tape, most hidden inside the light bowls. New repair cables from minispares and a clean up of the lucas terminals and all's good again. Thanks to all who suggested solutions.

[cal844]

POST SCRIPT

After a couple of days with a multimeter and no luck, I finally tracked down the problem to appalling wiring bodges on the front headlight looms. Dozens of poor splices, loose crimp terminals and insulation tape, most hidden inside the light bowls. New repair cables from minispares and a clean up of the lucas terminals and all's good again. Thanks to all who suggested solutions.

Glad to hear it's fixed, well done on finding the fault 😊