No ignition when i turn the key, confused ?

[martyn123]

Hi,

Rover v8 engine with carb and Megajolt system.

Confused as not messed with electrics but suddenly when i turn the key nothing happens, no ignition light, no indicators, no brake lights, no crank of the engine, no fuel pump noise, no oil pressure light all the usual stuff that comes on when ignition is turned to first point ready to start engine is not working.

All the other lights, dash lights, horn etc work and battery is charged, i am sure it's something stupid but wondered where to check first, do you get a fuse in this circuit ?

Note my megajolt system lights up okay when i turn the key to first turn and no wires appear to be loose on the ignition barrel

Still confused


Martyn

[ramon alban]

Hello Martyn, Cant really speak for the Mantula, just the conventional ignition switch system.

Normally no fuses involved en-route to the ignition circuit itself but the Ignition switch (position 2) also usually supplies the items you mention (as not working) thro' their individual FUSED circuits.

Therefore, your problem is almost certainly do do with the (normally) White wire output from the ignition switch or a white wire multi-plug connector immediately down-stream from the ignition switch.

To fix, flood the switch with switch cleaner or WD40 and likewise the local multi-plug connector.

You should also eyeball the same items for overheated white wire or connections thereabouts, due to overloads in the un-fused parts of the circuit.

If there are any burned wires or connections, you'll have to locate the short circuit (usually to earth, by a trapped or chaffed live wire) before firing up the repaired wiring/connector.

You might also be able to locate the source of the problem by wriggling the local connections mentioned whilst operating the switch.

In the same vein, the problem may also be with the 12 volt input wire to the ignition switch, usually brown, again because the other parts of the car that do work ok (dash lights, horn, etc) are not routed thro' or via the ignition switch.

Hope this helps? And good Luck!

[richardpope50]

I would first check the wires from the battery to each component with a multi-meter to see how far up the fault is. Use a wiring diagram to help trace each cable section for 12v so, for example first from battery to ignition switch. It's got to be simple and obvious.

[martyn123]

Hi,

Thanks for advice.

It really is difficult to get behind the dash to see the wiring but are almost certain no burned/overheated wiring. I can just about reach the two plastic loom connectors behind the dash and they are connected as they should be.

Before i try to delve further behind the dash to locate these white and brown wires i am wondering if a starter button that is used develops a fault would this have a knock on effect and disable the ignition and other fault that are occuring ? It was fitted last year and has been okay since fitted.

This really is confusing as i have not messed with the wiring and the fault appears to have appeared for no obvious reason.

[JSF55]

Last time i had to sort a problem like this, it was a poor connection on a connector that wa fitted to make the ignition switch easily changeable, one wire was fine the other no power at all, it was an 70's ford part, a good clean was sufficent, in the end i just bypassed the lot ! hth john

[richardpope50]

It does really sound like a loose connection as above. I had lots of problems with my starter and assumed it was the starter itself. Turned out to be the main bulkhead connector gradually coming apart (plug and socket arrangement).

There must be an easy way to get at the wiring even if it means taking off instruments, etc..

[martyn123]

So far,

I have a live brown wire at the key barrel

I turn the key and the white wire is then live, the white wire goes to a 10 amp fuse in the fuse box and have a live white at the fuse box when key is turned and the fuse is okay,

Normally when you turn the key to first position the fuel pump starts up and the instruments start working, fuel level, twitch on the tacho, ignition light on etc but getting nothing,


Next please ?

P.S. yes the battery is good, lights, horn all good...

[DaveEFI]

How are you measuring things? If you unplug a connector and look for 12v with a DVM, you may well get a totally wrong reading since a DVM takes no current. In other words, a switch or connector before that which is dirty may well have enough resistance so stop something working - but makes no difference to the reading on a high input impedance DVM.

Of course it can be more difficult to probe a connector etc that's still plugged in, so perhaps the easiest way is to use a test lamp - say 21 watt or so - and check it lights normally.

[martyn123]

Hi,

Finally sorted and thanks for the advice on here.

I managed to pull the fuse box forward and found a loose connection on one of the wire wires going into the fuse,


Result.

Just my windscreen wiper motor to repair now as it's playing up, i removed it from the car a couple of months ago, really awkward to get to and tested it on a bench and it worked fine, put it back in and yes it's playing up again, ah well it's not if i have nothing else to do.......will check it's getting power first.


Martyn....