Acknowledgement to Geoff McAuley who used the phrase, but this post is about the 50 years of using Josephine and the modifications to the standard electrics that are now employed on the car. Whilst there is always a discussion about restoring it to how it came out of the factory, I have decided to sympathetically include mods that I have previously used for touring, rallying and racing to make the car safer and more reliable.
There are five parts with some pictures of the components and installation as well as snippets from the circuit diagram. Also included are hints on fault finding such complex circuits.
1. Earthing.
2. Power distribution.
3. Battery circuits.
4. Ignition circuits.
5. Relays
1.1
Separate earths.
Many electrical problems stem from the Jupiter chassis, sub-frame and aluminium body all being electrically separate, especially if they have been freshly painted. There is also the issue of galvanic corrosion. The solution I used for the many continental rallies, where reliability was paramount, was to separately earth every component and take the earth wires back to a common point directly connected to the engine earth point (one of the upper suspension bolts) where a cable from the battery was also connected.
1.2
Cut-off switch
The earth cable from the battery is via a cut-off switch which was included after a loom issue when I first had the car and could be switched if any nasty smells or smoke were apparent.
1.3
Negative earth
Negative earth was also employed as some components need such. This is not so necessary these days as most are available positive earth. The only real change for Josephine is in the clock. This mod is explained in the ‘Early Javelin Restoration’ topic.
1.4
Terminal blocks.
Apart from earth cables that go to various components under the bonnet, most other earth cables go to two terminal blocks under the dash.
1.5
Single battery.
The original was fitted with two 6v batteries. These I changed to a single 12 v in the 1960’s.
1.6
Fault finding.
Even without separate earths you always need to check the earth return. At least with this system you do not have to contend with rusty steel or corroded aluminium. A wire connected to the negative terminal to the battery is used for the negative probe of the meter and the positive probe can be put on the earth point of the component. If anything other than zero volts is present when the component is supposed to be switched on, then there is a problem. With the battery disconnected continuity of the earth can be checked particularly where it is carried through connectors.
2.1
The positive feed.
Like the original, the battery cable goes to the starter solenoid on the bulkhead where the 500 amp cable continues to the starter through the relay contacts. Pressing the push button will test this circuit. Obviously make sure everyone is clear as the engine might start or be in gear.
2.2
The ammeter, power cut off and fuse board.
Power from the battery passes through the ammeter and another cut-off switch to the battery power distribution fuse board. This board has 10 blade fuses of different current capacity which are monitored by a clever LED circuit. If any fuse blows the relevant LED lights up. Much easier than taking out and inspecting every fuse!
2.3
The alternator.
Power from the alternator is fed via a 50 amp fuse to the ammeter side of the cut-off switch. Thus the ammeter will show a positive current if the battery is charging.
2.4
The discharge lamp.
On the dashboard this red warning lamp will glow with the ignition switched on and with the alternator not charging. Unlike a dynamo this is unlikely to occur with the engine running at low speed. The ammeter will also show negative charge if the alternator is not charging.
2.5
The ignition switch and ignition relay.
Fuse 1 feeds the ignition switch whose output feeds the discharge lamp, the starter push button, the electric petrol pump (which should start ticking), and the STEATH electronic ignition box of tricks. To reduce the load on the switch a lead also energises the Ignition relay that supplies a second block (see section 4) of 10 fuses via fuse 2. The ignition relay clicks when the ignition is switched on.
2.6
The starter.
The solenoid is energised via the starter push button with the ignition switched on. On Josephine power to the ignition switch is different as detailed above.
3.
The battery fuse block.
10 fuses supply battery power to various circuits.
F1. 25A. Ignition switch
F2. 15A. Ignition relay supplies power to ignition fuse block
F3. 10A. -Side light relay ( energised by the side position on the ignition switch) which feeds the 6 panel LEDs, front and rear sidelights, number plate light, the low intensity red and white LEDs on rear clusters.
- This circuit also feeds the rear fog light switch through to the fog warning lamp and high intensity red lights in the clusters. These lamps are also fed by the reverse relay when in reverse. The rear clusters are connected through a multipoint connector.
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This is shown not tucked away!
F4. 10A. – main beam headlight relay energised via the floor dip switch and headlamp switch position on the ignition switch. The relay output feeds the main beam warning light and the headlamps via the nearside bonnet connectors.
F5. 10A. – dipped headlight relay ( as for main beam)
F6. 10A. – Fog lamps are fed by relay energised by a feed from the sidelight relay and fog lamp switch. Normally head and dip are off in fog but can be on for driving on twisty roads.
- Spot lamps are fed by relay energised by a feed from the dipswitch (dip position) and the spot lamp switch. This gives a near and long field of view suitable for straight roads but requires switching off spot lamps to oncoming traffic.
F7. 5A. - Brake lights are fed via brake switch and multipoint connector. When the brake switch is activated it also feeds the rear fog relay that switches on the high intensity red LEDs in the clusters. The circuit has a flasher unit to further alert those behind and make it easy to distinguish between brake and side lights. The flasher does not operate the original brake lights which are continuous.
Click this link for a short video of their operation.
F8. 5A. – Reading lamp via switch.
F9. 5A. – USB power and cigar lighter socket via fuse and switch for all those modern devices.
F10. 20A. – Radiator fan relay which feeds radiator fan. The relay is energised by the front panel adjustable thermostat and the fan switch which receives power via Fuse 19 which also feeds the oil and water temperature gauges. This means the rad fan is switched off with the ignition so if the engine is hot it would be advisable to switch the ignition back on to allow the engine to cool. It has been known for the fan to drain the battery in very hot conditions otherwise.
4.
IGNITION FUSE BLOCK
F11. 5A. – Petrol gauge and then to tank sender.
F12. 5A. – Brake switch to brake lights and rear fog relay.
Are the connectors to the brake switch. A second spare switch has been installed as I have found the microswitch type to be more reliable. Currently it is not connected.
F13. 5A.- Indicator switch each side has a separate flasher relay that feeds the front and rear LED cluster. The green warning lamp is also on each circuit and both circuits are energised by the hazard double pole switch
Click this link for a short video of their operation.
F14. 20A. – Horn relay power feeds the twin tone horns.
F15. 10A. – heater via rheostat , yellow warning lamp
- Washer via push button.
- Wiper via switch, blue warning lamp.
F16. spare
F17. 5A. – Horn relay energising circuit by the dash horn push button or the steering column horn push.
F18. 5A.- reverse switch and relay. Normally open position gives output to high intensity red lights on rear clusters when reverse engaged.
-Normally closed position feeds the overdrive switch which energises the overdrive relay which is also fed by this fuse so that the overdrive is engaged and lights the orange warning lamp. This relay output also goes to the clutch relay which if the clutch is not depressed latches the overdrive on. Note the overdrive will not come on if the reverse switch thinks it is engaged.
-To switch into overdrive the overdrive switch only needs to be momentarily switched. To switch out of overdrive the clutch should be momentarily depressed or the clutch fully engaged to change down a gear as well as switching out of overdrive. This arrangement gives some flexibility on gear/overdrive selection and is found to be much faster and easier during rallying, particularly with the torquey Jowett engine. The overdrive can be held in by leaving the overdrive switch down and thus on.
Two clutch switches have been installed. The original reliable microswitch pulled by springs and a new button type that closes when pedal returns. The latter is currently employed.
F19. 5A. Temperature panel. As outlined in Fuse 10 above this fuse feeds power to the fan switch and thermostat. It also feeds the water temperature gauge and sender in each head via a switch which toggles between them. This arrangement is useful to see differences in temperature perhaps caused by burning valve or leaking gasket. It also can show issues when compared to the header tank temperature gauge. The oil temperature gauge with its sender in the oil thermostat output pipe can be used in conjunction with the oil sump temperature. The oil thermostat by-passes the oil cooler if the oil temperature is low.
The rheostat is for accurately adjusting the boiling point on the gauge as I find the senders can differ.
F20. 5A. – clock which has been switched to negative earth by changing polarity of diode in it. Note the clock only works with the ignition on but this saves its precious contacts. So one could think of it as one of these modern elapsed engine hours gauges!
5.
Relays.
Originally the Jupiter only had two relays if you ignore the two in the regulator. They were the starter solenoid and the horn relay. They were there because otherwise the switches would burn out. The starter takes 500A and the horn about 30A.
I have also had problems with some other Jowett switches over the years and long ago started to use more relays. I also needed some quite complex switching for the lights when rallying. I also used microswitches for control of overdrive and reversing so relays were necessary to switch the currents required.
The ones I use now are rated at 30A and have a normally closed and normally open output. They are also pluggable so are easily changed, although in 30 years I have not had one fail.
Here is the list.
Ignition, Sidelight, Headlight, Dipped beam, Fog light, Spot light and radiator fan are on the battery power.
Horn, Flasher nearside, Flasher offside, Flasher for brake and reverse high intensity cluster LEDs, Brake (used for high intensity rear light), Reverse (uses both NO and NC), Clutch (used for overdrive latch) and Overdrive are on ignition power.
The SCHEMATIC.
Here is the complete schematic. I have some of the subsystems in separate pages which I may upload. It is best viewed
by clicking this link and opening in a separate window.. Clicking this thumbnail brings up the Gallery item where there are two resolutions to choose from.
