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Hiding electrical gremlins

J

JimMW

Accelerating Away
Well ive had my first landy two weeks and sorted most of the mechanical issues, but I have to admit that I am awful with electrics.

Firstly, when I bought the car the fuel and water temp gauges did not work, but the alternator charge light did. Then about a week ago they worked and two days later were on the blink. Had a butchers behind the dash panel and nothing seems to be loose or wrong.

Secondly, Yesterday my indicators and wipers packed up, but come on when they feel like it every once in a while. Heater is intermittently powered as well.

Dash lights dont and have never worked.

I was wondering whether any one has any suggestions why these aren't working as they are intermittent faults and seem to work/break in groups of two or three pieces of equipment??

Also was wondering whether the car should have hazards Its an 81 SWB petrol??
 
sounds like yet another case of Lucas (Prince of Darkness) syndrome...

when things crap out in clusters like that, look for common feeds and / or common grounds...

based on lessons learned, I'd start by popping each fuse one at a time, checking the fuse contacts for corrosion, check the fuse contact block for corrosion before refitting and checking the next fuse... Then check that the ground lines actually DO have a path to a conductive ground, not merely a screw held by a self tapper driven into a nice patch of rust...

it's dead boring, damn frustrating and ya get little thanks for it, but with old electrics, it pays to be meticulous...

if that lot fails to resurect the affected stuff, you need to start using a volt meter to tell exactly what's going on (or not as the case may be)..
 
A good place it to start with the wiring diagram and look for a point where all the affected circuits are common, ie a fuse or switch or earth then check all these out, A mutimeter is the best way though, follow the circuit backwards from the non working component looking for voltage drops.

kevin
 
The instrument lights should be simple - the switch takes a feed form the main light switch. Just disconnect the instr light out put wire and connect it directly to the main light switch-instr light switch output, bypassing the instr switch. If that works, leave it. If not, have a look at the earths on the speedo and combined cluster mountings (black wires with ring terminals, attached to one of the three clamping bolts of each gauge unit).

The indicators are likley to be a faulty flasher relay or stalk switch. Tyy bypassing the switch to see if you can control them directly. If they work, you have identified the switch as the problem. If not, then it's likely to be the flasher.

The faulty fuel and temp gauges are likely to be a bad voltage stabiliser, but the fuses and connections are worth a close look too. The blade termonals on the top of the fuse box corrode and give poor contact, so removing the fuse box and cleaning each terminal with fine emery paper can work wonders. This could help with the indicators, too, as they get their power from the fuse box.
 
Snagger said:
so removing the fuse box and cleaning each terminal with fine emery paper can work wonders. This could help with the indicators, too, as they get their power from the fuse box.
Click to expand...

I also found that removing eash fuse and cleaning up the ends with emery worked wonders on mine also!
 
I'd also say have alook at the fuse box. At one stage I used to leave the cover off so I could 'waggle' the fuses while I was driving when various electrical items packed up.

I used to keep a piece of emery paper in the car to clean up the fuse contacts as well if waggling didn't work.
 
BillScarab said:
I'd also say have alook at the fuse box. At one stage I used to leave the cover off so I could 'waggle' the fuses while I was driving when various electrical items packed up.

I used to keep a piece of emery paper in the car to clean up the fuse contacts as well if waggling didn't work.
Click to expand...
It's not just the lower ends of the terminals that grip the fuses, but also the top ends which are blade connectors for the wiring loom to connect to. They caused problems for my indicators, head light and horn switch.
 
Thank you for the advice guys, I replaced all of the fuses and cleaned fuse box terminals today, they looked pretty rotten to be honest and, hey presto the indicators and wipers work :D.

Fuel and water temp are still not working at all but I shall try rewiring the dash lights to exclude the switch tomorrow.

N.B Must carry emery paper on all future outings :eek:

Thanks Again

Jim
 
Did you clean the terminals on top of the fuse box? One of those green wires goes to the voltage stabiliser (mounted on the back of the speedo), and from there goes to the fuel and temperature gauges. They then independently earth via their "sender units", and a simultaneous failure of both senders is unlikely. It's likley that the corroded fuse box terminals are preventing a good current from reaching the voltage stabiliser.

As for the lights, the bypassing of the instrument light switch is just a quick check to eliminate it as a fault. It's unlikley that the switch is the problem - it's rated at 10A but caries no more than 1A at peak loads to the two small bulbs. I bypassed mine permanently because I can't see the need for running the external lights without the instrument lights, and use the switch to run my fog lights. Blown bulbs are a possibility, but the earth is the most likely fault.
 
To check if the voltage stabaliser is at fault you can just plug the gauges straight into a 12v supply.. and they should read (although very high). My voltage stabaliser killed itself up in the lake district so I just bypassed it and just used the gauges accepting that they were going to read about 25% high all the time!

So 1/4 tank of petrol meant I was On fumes, and being in red on the temp gauge ment everything was hunky dorey!

I made my own replacement stabaliser here https://www.lrukforums.com/showthread.php?t=153655.. cost me about £1 in materials :D I havee taken one of the guys advice and mounted it on the back of the speedo now to help disipate heat!
 
Had another route around in the dash today, sorted all of the previous questions asked so thanks to all those that gave great advice, and my dash illumination is now wired in with the headlamps. :cool:

Found some interesting wiring in there though, It seems one of the POs have tried their best to install a radio/cassette. Got all the euro plug adaptors but the damn thing is wired in to a permanent live from the battery. WITH HOUSEHOLD THREE CORE CABLE.:eek:

I presume that to wire a radio in properly that I would need a permanent fused live from the battery maybe, and a controlled live from the ignition and an earth. Would like to hear your thoughts about what stuff to put in but I might just go to the scappy and haul out some speakers from something half decent that has been crashed/scapped.

All opinions shall be taken into account and please talk as if you were talking to an electronics numpty. Because I am one.

Jim
 
JimMW said:
I presume that to wire a radio in properly that I would need a permanent fused live from the battery maybe, and a controlled live from the ignition and an earth. Would like to hear your thoughts about what stuff to put in but I might just go to the scappy and haul out some speakers from something half decent that has been crashed/scapped.
Click to expand...

I just have mine with a permenant fused live, meaning I have to switch it off when I switch the engine off. However it does mean I can put the radio on without the ignition being on which is usefull when working on the truck.

However to do it properly you can take your permenant live and switched live from the back of the fuse box (fused side)

I don't remember which, but two of the fuses will be permenant lives, and the other two are ignition lives! At least this way when you start the truck the radio will come on!
 
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