SLROC Forum

When it comes to vehicle electrics I am for want of a better word a muppet ! Thats probably slightly unfair as I can do the basics, wire in lights and switches that sort of stuff but as far as diagnosing problems well I'm a bit lacking . Two problems , firstly the heater blower motor . This appears to be somewhat intermittent, ie can blow almost non existently and then without prompting can speed up. Always appears to have power though.Plenty of heat coming though but just very little power and a  little ad hoc . Is this a earth fault perhaps if the power is up and down ? Same also applies for the wiper motor which sweeps slowly and again can speed up when it wishes. Furthermore one wiper blade doesn't always complete a full sweep but then again does if it wishes. Is this another earthing issue and can anyone tell me where the earths are located for either of these parts ?
I was going to test the heater motor first of all by disconnecting the wires at the motor and running it straight to battery. Then I was going to test the power at the selector switch on dash by bypassing it altogether to see what it's like at single speed without being regulated . Any ideas or pointers would be appreciated .It's a 110 btw.

on the wipers, check the grub screw in the boss that the arm sits on is tight

Geoff

Earthing on Land Rovers, especially those that are mostly alloy is always a possible cause of intermittent faults but mostly cause a failure to operate rather than the symptoms you suggest. Sounds like the speed of the wiper and blower motors is changing with the balance between load and supply. Quite simply if you rev the engine and your alternator then speeds up you will generate a better supply therefore you may find that the motors speed up with engine speed. Similarly, if your vehicle has an electric radiator fan or heated rear window then the motors slow down when these are on.

If this is what is hapening then this would point to a weak battery or a faulty voltage regulator, basically
your vehicle is reponding to how much juice the alternator is putting out rather than a nice steady 12V+ from a well regulated healthy battery? If you know someone with an electrical meter then ask them to measure the volts at some convenient point and the nearest bare metal. Rev the engine to see if it changes much. Suitable point would be an interior light fitting. Take the lamp cover off, remove the bulb and the end with the wire attached should be positive, normally the other side of the fitting gets earthed via the fixing screws to the body.

Geoff, checked the wiper already at point you suggested and it's fine .
Boghog. Never had any problems with the battery as engine starts first time, every time and on the button . With regards to the heater motor what I have noticed is if you have the ignition on and engine off or running at idle the heater motor runs at a moderately quicker speed than if you were driving. Can't say the same about the wiper motor. I take it the voltage regulator is part of alternator ? Another thing is that the voltmeter guage does sit high, in fact off the scale every time .

Assuming you own a Defender then from what I can tell from the useless manual (begins with H and ends with aynes) it looks like the blower and wipers won't be part of the regulated circuit so probably nothing to do with your issue. If it has a regulator (seems to be called a voltage transformer on the manual) then it is probably behind or attached to the instrument (speedo) panel as it was on Series Land Rovers. It helps make sure the instruments maintain a reliable reading regardless of the electrical load. The manual mentions a 'voltage switching relay' located behind the speedo panel and maybe this does do something, can't find it on the schematic!

Going back to the earthing points, the main one on the Series vehicles used to be under the seat box, driver's side, also a big hefty strap from the gearbox casing to chassis for the starter motor. Suspect Defender is similar. Sounds like your main earth is fine if the starting is spot on.

Thanks for that . I'll have a look over the weekend .