Jensen heritage for the next generation

Electrical System

Dear Diary discusses the electrical system to Jensen FF chassis number 119/191

From the Jensen FF Mk1 sales literature: The electrical system consists of the following: “12 volt 40 amp alternator with 6 silicon rectifiers. Voltage regulator. Battery 67 a/h. Twin sealed beam headlights with side flasher switch incorporated in turn indictor control. Side and rear lights, number plate, engine compartment and boot illumination lights. Rheostat controlled instrument light. Interior light with courtesy switches on doors. Rear interior lights with combined switches. Twin bladed two speed self parking electric windscreen wipers with anti-lift blades and screen washers. Illuminated cigar lighter. Reversing lights operated by switch incorporated in gear selector mechanism. Illuminated electric clock. Self canceling turn indicators with warning lights. Electrically operated windows. Red warning lights in door trailing edges.”

From the Handbook of Instructions for the FF (October 1969): Wiring Diagram. Note: this shows the oil pressure warning lightand the brake fluid reservoir warning switches.on the later MK1

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Photo showing open fuse box, with the box containing the relays in front. Also radiator expansion tank.


The big red thing at the bottom of the photo is the pump for some aftermarket air horns.


Photo showing the remote starter button.


Replacing the Motor gear.

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Access is obtained by removing the door trim and the door speaker( see photo 1). The motor has an upper bracket with one securing bolt and three bolts on the motor itself (see photos 2 and 3). There is just sufficient space between the outer door skin and motor to undo these three bolts. There are two wires to the motor. Both are live wires and if you get them the wrong way round when you put them back the window operating switch will work in reverse. Once removed it is a simple matter of removing the Philip head screws, taking out the old drive unit and replacing it with the new uprated nylon one that also has the shock absorbing springs built in (see photo 4)These were obtained from Cropredy Bridge Garage Riverside Works Cropredy, Banbury OX17 1pQ England. Tel. 01295 758444. Fax: 01295 750446.They have them as part No. 4339433 (“GEAR,WINDOW MOTOR”) at £20.20p + VAT.each. I put a little “copperease” grease on the moving parts before replacing the cover. A good tip I was given was that, before putting the three “motor bolts” back in, to cut a slot in their tops, which will help you reinstall them (and remove them if necessary at a later date) using a screwdriver ( see photo 5). Replace the motor. You may need to manoeuvre it a little or even connect up the power leads to rotate the new cog in order that it relocates itself properly.


I bought a standard central locking kit (£25) and a separate remote car alarm kit with interior movement detector(£30). Both off E-Bay. The remote operated alarm came with a feed to the central locking (as most do these days). The result was an alarm with interior movement sensor and remote central locking. Some 4 weeks on when compiling this information I can honestly say it is all working very well. The best bit is not having to use keys and having to lean across to open/close the passenger door.

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Photos of Central locking box/kit (minus one motor which I had already fitted by the time I remembered to take this photo).


photo of the motor showing its location in front of the door panel where it will go. Held in place by two screws.


Photo showing the small 3/8 th inch hole being drilled. This will the allow the rod from the central locking motor to come through for connection to the existing locking knob rod

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photos showing the long connecting rod from the central locking motor and the connection of the two rods, one from the central locking motor and the other, the existing rod between the lock and push/pull locking knob of the door.


Photo of inside of door showing the recess that makes the shape of the door a perfect fit for the central locking motor and operating rod

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The drivers shelf was loosened and the wires fed up behind the panel and to the control module, which itself was placed behind the panel housing the air flap control. This gap is a non usable void which I believe will allow easy access in the event of problems.


Fitting the wiring for the central locking was much harder than the motors. All the connectors were already in place but the wires needed to be fed through the door into the cockpit and the existing route for the speaker and electric window wires was not large enough.


I had to remove the side panel in the footwell to gain access to drill though the “A” post


I drilled new holes through the end of the door and “A” post just below the existing holes for the other wires. The sharp edges of the holes were ground down with a grinding stone on a Dremel and then protected with grommets and finally the wires were encased in a flexible plastic tube to protect them.

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The single screws that hold each of the two pods containing the speedometer and alternator were removed and the pods loosened off .The centre pod where the radio is, was also removed and the wires from the left hand (passenger) door fed behind the facia to the central locking control module.


Although not so easy to do as the drivers side the wires were fed up into the void behind the facia and then to the control module.

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Photos of the alarm box and movement sensor in its proposed location.



A 60 amp feed wire (bought from Halfords in car entertainment section and which is used to feed large amplifiers) is now connected to the feed from the alternator and leads, via a 40 amp in line fuse to a 4-way copper block connector (again from Halfords ICE centre). The block has a single input and 4 outputs. Presently one of these has 2 17 amp wire connected to it as the feeds to the 2 Bosch fans (via 2 realys).

I have now also improved the wiring to the fans as the Bosch fans draw 10 amps each as opposed to the Lucas ones at 7 amps each. One of the best places for electric stuff is Auto sparks ( They will also send a free catalogue. I bought a few metres of 17 amp pvc cable (size 28 in catalogue) and wired each fan motor separetelly with its own fused relay.