if i put a meter across the battery on my rs turbo s2 i get 13.15 volts when engine idling, will not change if i increase the revs, if i measure the voltage when engine off it measures 12.4 volts. im pretty sure that the volts should rise to about 14 volts when increasing the revs, any ideas what the problem could be, have checked the earthing to the engine.

steve

 

Is the belt loose?

 

nope, checked that,

 

if i splice into the insulation on the thin blue wire going to the alternator and put a meter across this wire and negative on battery, i have o volts when engine off, 14.2 volts when engine idling and increases to 14.35 volts when increasing engine revs

 

That sounds fine. You could try with engine running switching headlights on and say blower it should not drop below 13V under load.

Martin

 

In that case will be heavy gauge wire (From B terminal) that goes to battery that probably needs replacing.

The blue wire you refer to excites the field windings that starts the charge process it will have 12V + with ignition on and output from alternator with engine running. (Thats how battery light extinguishes as to lives=no good)

Also check battery and engine earths.

Martin

 

hi martin, there is 2 thick wires coming from alternator, does one go to starter motor and the other to the battery, have put a meter across both the thick wires and the thick red/blue wire to the battery, i have no continuity does it go to a fuse first before it goes to the battery, does anyone have a wiring diagram for a 1988 rs turbo they could email me, thanks

steve

 

fella do the original test again but get someone to start the car while u watch the meter you should not go down below 9 volts on cranking and it should recover fairly quickly the fact that the voltage rises when u start the car means the alternator is working [the blue wire goes direct to the warning light on the dash the red wires go to the top of the starter motor hope this helps

 

thanks for the help, have run new cable from alternator to battery now charging battery 14 + volts, just need to find where i can wire the cooling fans to now.

steve

 

Don't know your car so can't say what 2nd heavy gauge red wire goes but one defentily will go to battery either directly or indirectly via another component, Starter motor for instance.

The fact you have good power from alternator itself and not at battery shows the problem to be with the feed not surprising considering the age of the wiring! May just need terminals cleaning both ends.

Martin

 

read yr other post fella

 

Ford had a nasty habit of using cheapo wire, that was a mix, not pure copper, this soon builds a resistance, as does the joint where the battery/alternator lead join.
Even a thin wire of 14/030 will help things markedly with this problem, the things that are paticularly affected are DC motors, such as windows, wipers, fan motors, 1 volt difference can make a huge difference.
The way to test is simply to check at idle with just engine running, then again with lights heater etc on, when raised to 2000rpm so long as you have a minimum of 12.8 will be fine when lights etc are on.
The on starter current could easily dip to 7/8 volts on a cold day momentarily, but this is onlya few secs and does no damage, ecu will work down to a low enough voltage.
tabetha