Couple Of Electric Problems

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EddSeriesIII

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Hi, Just brought a diesel Series III Land Rover which i'm fixing up, but I need some info on some of the electrics.

1. The glow plug light is very dim, it only just glows. I traced all the wiring and it all seems fine according to the Haynes manual. Across the resistor measures around 6v, but I have a 12v bulb for the glowplug light. Has someone put the wrong bulb in at some point or is this correct? Do I need a 6v bulb?

2. In the middle theres a panel with a light saying "Brake". I thought maybe a hand brake warning light, but I cannot find any wires coming out of the drum or lever. It doesn't come on with handbrake. Haynes manual doesn't even method it, so I really need to know what it's for.

Many Thanks
 
where in the circuit is this resistor you mention ? - if your seeing 6v across it that's volts drop and not the same as you would see across the bulb - have you pulled the bulb out of it's holder ? - is it bright ? - the holder/lens do get very dirty and could give the impression of a dim bulb - measure the voltage across the bulb terminals

there's a switch attached to the pedal that turns on the brake warning light - but only if there is exccesive travel ie lack of fluid/low pads etc
 
where in the circuit is this resistor you mention ? - if your seeing 6v across it that's volts drop and not the same as you would see across the bulb - have you pulled the bulb out of it's holder ? - is it bright ? - the holder/lens do get very dirty and could give the impression of a dim bulb - measure the voltage across the bulb terminals
Click to expand...

Thanks for your reply.

I was talking about the resistor on the bulkhead. The wires for the glow plug light connect to either side of it. I have pulled the bulb out, and tried it in another warning lamp and it works fine. The voltage across the bulb terminals was still 6v. I have noticed the wires leading to the light had 'fused' to a few other wires in the dash, so it's getting hot for some reason. I think I might first try replacing the wiring for the light back to the resistor and see how I get on.

there's a switch attached to the pedal that turns on the brake warning light - but only if there is exccesive travel ie lack of fluid/low pads etc
Click to expand...

Thankyou I have a look for this and check it works.
 
I also have a diesel series 3. I had the same problem with my light. It was so dim, I thought it was burnt out. I was told that the glow plugs in my engine had been replaced at some point of the vehicle's life.
The originals were wired in series (a daisy-chain, when one burns out, they all stop working), but the ones I had were replacements wired in parellel. I guess they draw less current draw through the light circuit, making the light dimmer.
This has to do with the way that the circuit is wired... with positive voltage on both sides of the bulb, the bulb will only glow with an amp draw due to a change in voltage from one side of the bulb to the other. In theory, the amps that the glow plugs are drawing across both the resistor and the light circuit (that acts as a bypass for the resistor) will make the bulb glow. Good theory, and if you had new series-wired glow plugs and a new resistor, the light might really glow brighter... But, it is still a 12 volt bulb on a 6 volt circuit, it will still be dim.

You can rewire the circuit so that it is alot brighter, without all the amps... Disconnect the White/Blue stripe wire from the resistor and connect it to ground. Problem solved. Before I replaced my 2.25D for a 200TDI I wired it this way and it works just fine.
 
Oh, one other thing... The "Brake" light is an indicator for low brake pressure. Follow the brake lines from the brake master cylinder down to the chassis. They will come to a small pressure block that has an electrical switch on it. The manual calls this the "brake pressure differential warning switch". It will light up if there is a pressure fault in the braking system.
 
rjblank said:
Oh, one other thing... The "Brake" light is an indicator for low brake pressure. Follow the brake lines from the brake master cylinder down to the chassis. They will come to a small pressure block that has an electrical switch on it. The manual calls this the "brake pressure differential warning switch". It will light up if there is a pressure fault in the braking system.
Click to expand...
not all series 3's have them,i think it's only dual line braking systems that do.
 
bigchap said:
not all series 3's have them,i think it's only dual line braking systems that do.
Click to expand...
Why am I not surprised? They also have oil bath air cleaners... Before owning my Land Rover, I thought that ALL car companies stopped using oil bath air cleaners in 1960!
 
The brake warning light is normally located amongst the switches on the instrument panel. It is only present where dual circuit master cylinder is fitted, and these seem to have been fitted to lots of series 3 landies regardless of age. You need it working, as it should come on if either the front or rear brake circuit springs a leak and loses pressure.

I suspect that you would notice the loss of 50% of your (already feeble )braking power though without it...........:D
 
I also have a diesel series 3. I had the same problem with my light. It was so dim, I thought it was burnt out. I was told that the glow plugs in my engine had been replaced at some point of the vehicle's life.
The originals were wired in series (a daisy-chain, when one burns out, they all stop working), but the ones I had were replacements wired in parellel. I guess they draw less current draw through the light circuit, making the light dimmer.
This has to do with the way that the circuit is wired... with positive voltage on both sides of the bulb, the bulb will only glow with an amp draw due to a change in voltage from one side of the bulb to the other. In theory, the amps that the glow plugs are drawing across both the resistor and the light circuit (that acts as a bypass for the resistor) will make the bulb glow. Good theory, and if you had new series-wired glow plugs and a new resistor, the light might really glow brighter... But, it is still a 12 volt bulb on a 6 volt circuit, it will still be dim.

You can rewire the circuit so that it is alot brighter, without all the amps... Disconnect the White/Blue stripe wire from the resistor and connect it to ground. Problem solved. Before I replaced my 2.25D for a 200TDI I wired it this way and it works just fine.
Click to expand...

Sorry I did not get back sooner. My Series III also had the updated parellel wired glow plugs. I did like you said and wired the blue/white wire to an earth in the dash board and it works great now. Thankyou.

The brake warning light is normally located amongst the switches on the instrument panel. It is only present where dual circuit master cylinder is fitted, and these seem to have been fitted to lots of series 3 landies regardless of age. You need it working, as it should come on if either the front or rear brake circuit springs a leak and loses pressure.

I suspect that you would notice the loss of 50% of your (already feeble )braking power though without it...........
Click to expand...

I dont think the warning light works. I have not had time to look at it yet, but I know the brakes hardly stop at all. Need new wheel cylinders, easy fix. I'm more concerned now why the battery keeps going flat. Something must be shorting to earth and finding it could take a while.
 
rjblank said:
Oh, one other thing... The "Brake" light is an indicator for low brake pressure. Follow the brake lines from the brake master cylinder down to the chassis. They will come to a small pressure block that has an electrical switch on it. The manual calls this the "brake pressure differential warning switch". It will light up if there is a pressure fault in the braking system.
Click to expand...
Thanks, I've always wondered what bpdw switch in the parts book meant (I knew what it was)
 
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