72 Sprint Fed Wiring Diagram

[memini55]

Sorry if this is a repeat but looked in the archives and did not find much but I seem to remeber a drawing somewhere. I am helping put a 72 Sprint back together for a close freind. He had taken it apart about 6-8 years ago and cut most of the harness out. He bought a new harness from Autospark and has asked me to help install. It is similar in some ways to the S4 drawing but different with the flasher relay under dash and the headlight switch wiring. I have the dash out and trying to build it back together out of the car first as it is much easier.
I have everything sorted in the boot and under the bonnet. Got a reasonable handle on the dash but the hazard switch and headlight switch and relay seem confusing.
I did read a post about the need for the rely and recommendation to look at a fed Europa drawing which I have and will do shortly.
One other area of question is the cold start circut for the coil and blast resistor. If I understand that right a swtched hot off the starter solenod goes to the coil to give full voltage during start crank and the ignition white would connect thru the blast resistor and once start is relaxed then provide voltage to the coil?


Any help would be great!
Thanks
Mark

[garyeanderson]

Hi Mark

I "helped" a friend with his customers Federal Sprint 4 or so years ago. I had the same problems to make both the hazzards and directionals work, I could get one to function but not the other and vice versa . That circuit was not anything like how the S4 diagram was drawn at all by the time I had it all working. I made up a "memory reminder drawing" but left it with my friend, he may have it and I will ask when I see him. The gyst of it was I had to power the DB10 relay with an "always hot" feed wire to get the the flashers and directionals to work. sorry I can't say more but the diagram was not helpful. I think I may have used the plus2 diagram for a start on the DB10 portion of the circuit, I spent the better part of a day (maybe longer) just to get the hazzards and directionals to function at the same time and in the end I believe that directionals and hazzards both workd without the key in the ignition.

Gary

p.s. I will be quiet today, going out to Lime Rock for the "fall finally" to See Dave's mkIX get some excercise. I will post photos for those that enjoy that type of thing.

[neilsjuke]

I find sometimes it is best to do a bench hot/soak test with the relays switch bulbs etc, This will get the circit it your head and you will know the parts are working replacement looms can cover a range of models and this will not relate to the diagram or model . I have a set of bulbs with wire soldered on ,range resetable circuit breakers and test leads with croc clips.
Neil

[memini55]

Thanks guys

I have had a look at my +2 and Europa and found the flasher relay detail and some help with the headlight switch. It also shows the cold start circut.
Still would be nice to find a factory diagram and as you said Gary I will make my own drawing when finished for future reference.

Ain't wiring fun!!!

[Frank Howard]

the ... headlight switch and relay seem confusing.

Mark,

I have performed some extensive rewiring on my S4. Perhaps I can help. There is always a 12V connection to both sides of the relay, the switching side and the connection side. When you pull out the dash switch, you are completing a circuit that starts at the battery, runs to the switching side of the relay, goes through the dip switch, goes to the dash switch, and then goes to ground. When this happens, the switching side of the relay mechanically throws a switch on the other side of the relay, the connection side. This completes a second circuit which starts at the battery, goes to the connection side of the relay and because the switch inside the relay has been thrown, can now make it's way to the headlights and then to ground.

If you flip the dip switch up, you break this circuit and complete another one, this time through the high beam relay which is connected to the dash switch through an alternative route which is determined by the position of the dip switch. I realize this is not the way Lotus did it as they have the switching side of the relays wired the opposite way. They run 12V to the dash switch, through the dip switch, to the relay, and then to ground. I just found it more convenient to have the 12V go to both sides of the relay as this can be accomplished with one wire from the battery.

One other area of question is the cold start circut for the coil and blast resistor. If I understand that right a swtched hot off the starter solenod goes to the coil to give full voltage during start crank and the ignition white would connect thru the blast resistor and once start is relaxed then provide voltage to the coil?

Depends on which starter you are using. If you're using the standard Lucas starter with remote solenoid, then your assumption is correct. If you're using a Super Starter, there is a provision for this on the starter itself because the solenoid is attached to the starter.

Call me if you have any more questions Mark. You know how to get hold of me.

[dlbarnes1]

As Gary indicated, the Fed Sprint wiring differs considerably from the S4 wiring diagram in the Workshop Manual. The principal differences are the presence of the DB10 relay; and, the circuits for the headlamps, indicator/stop lamps and hazard switch.

There does not seem to be a "factory" wiring diagram for the Fed Sprint. Perhaps one was issued as a Service Bulletin. Does anybody know? There is a diagram for the +2S Federal that can be used as a guide since it includes the DB10 relay, etc.

The headlamp circuit for the Fed Sprint is generally like what Frank described for rewiring on his S4. The key points being that voltage (unswitched) goes to the dip switch which energizes either the main or dip relay with the circuit being completed thru the lamp switch/operating valve to ground. When either relay is energized, it connects voltage (unswitched) to the main or dip filament on the headlamps.

The circuits for the indicator/stop lamps and hazard switch in conjunction with the DB10 relay cannot easily be described without a diagram. The purpose of the DB10 relay, as far as I know, is to allow a single filament to be used for the indicator/stop lamps.

The lamp switch/operating valve has two microswitches. Another difference, I think, between the S4 and Fed Sprint. One of the microswitches connects to ground for the headlamp relay circuit. The other microswitch connects voltage to the tail, side, and parking lamp circuits.

Dave 72 Sprint DHC (Federal)