Why are S30 electrics so weak?

[Rob Gaskin]

I've had an ignition issue this weekend which might be related so the question is why does S30 electrical 'stuff' need the engine running to work?

Even the indicators don't flash at the correct speed unless the engine is running. I've had this on more than one car.

 

[Alphabettispaghetti]

whats the resting voltage in your battery?

 

[datsfun]

I think you will find compared to British and Italian cars of same vintage, they are far superior.

 

[Jimbo]

resistance unfortunately and the distinct lack of relay use.
you could upgrade it all but its not an easy task if you dont know what your doing.
upgrading the headlight circuit with relays will help reduce the load on the old system.
other than that upgrading the alternator would make a big difference especially if you can reduce the diameter of the alternator pulley.

 

[Rob Gaskin]

I have heavy duty batteries fully charged. Upgraded alternators yes (well 60A) but of course I'm asking why the engine has to be running at all. I do have a reasonable electrical knowledge tbh. I have relayed headlights.

I have upgraded my wipers to Honda too - huge improvement.

Guys try this - switch your ignition on and try the indicators. Do they operate correctly i.e. flash consistently?

 

[MaximG]

Yep

 

[Paul_S]

Mine cause the fuel pump (on a relay) to go off and on when the engine's not running!

 

[jonbills]

Yep

Mine too.

 

[Farmer42]

Mine too.

Ditto. You must have a resistance in the circuit somewhere that stops your flasher unit operating properly. Either that or it's duff! Dry solders on the ignition switch or corroded bulb holders can cause it.

 

[Jimbo]

test voltage at the relay and see if your getting battery voltage
i will be very suprised if you do.
when the battery is charging off the alternator the voltage must be higher than battery voltage, this in turn is what the circuits in the car are designed to run at.
when you turn the engine off the voltage will be lower and therefore everything appears to run slower, this isnt a fault its just the way it is.
age makes it worse with the forementioned resistance and other age related issues.
modern cars are better regulated (power operating things is regulated to 12v irrespective of alternator output, this is why its not uncommon for modern alternators to output 16volt to charge a battery but not effect the rest of the cars electrics) they are ecu controlled with a myriad or relays sending power along the shortest route so losses are minimalised.
this can be replicated on old cars but its probably worth just living with the quirky electrics

 

[uk66fastback]

Great knowledge Jimbo!

 

[Alphabettispaghetti]

The reason to test voltage at the battery, is to see what the 'resting' voltage is, then test along the circuit. to find out where the excess of resistance is.

 

[Jake RAH]

Mine too.

My next door neighbours house lights flash on & off when I do that. Is that ok?

 

[johnymd]

As you know Rob, electric are very very simple. High resistance causes a volt drop so you end up with less voltage at the load. Lessen the resistance in the entire circuit (to and from the load) ( people often forget about the path back to the battery) and your load will work better as it has more voltage across it. Simple.

As the wiring, switches and connections age their resistances increase a little but eventually all add up to make a big difference.

 

[Rob Gaskin]

Thanks guys, that's very helpful. I thought it was just old switches and components.

 

[MaximG]

It might be worth checking your earth point Rob. You have the obvious one in the engine bay attached to the bolt that holds the break thingy to the inner wing. But there is also probably a lesser known one by the fuel tank which might be worth cleaning up.

Mike

 

[Rob Gaskin]

All of you above (apart from Jake ) were spot-on. Thanks.

 

[johnymd]

On pretty much all the zeds I build now, I replace the entire wiring with an EZ wiring harness. I know its not original and factory but it is reliable and works well. The hardest part is connecting things like steering column controls, wipers and heater but its all simple once you get your head around it. The kit is around £100 and the fusebox and relays are pre wired so you just connect up the controls and the end of each circuit.

 

[Alphabettispaghetti]

Thanks guys, that's very helpful. I thought it was just old switches and components.

you seem to be unlucky with how butchered yours is Rob.

 

[Rob Gaskin]

On pretty much all the zeds I build now, I replace the entire wiring with an EZ wiring harness. I know its not original and factory but it is reliable and works well. The hardest part is connecting things like steering column controls, wipers and heater but its all simple once you get your head around it. The kit is around £100 and the fusebox and relays are pre wired so you just connect up the controls and the end of each circuit.

Good idea John. My front-end is sorted now and my back-end. The dash loom is on the bench and after many hours of tracing and learning I'm going to modify it for my specific car. I'll write all this up later.

Column controls - I bought a Subaru system to install but I may not do that.