Dash layout for 3.5 saloon

Recently bought 1946 3.5 litre saloon but various dials and switches been replaced, not connected to anything and am trying to work out what should be connected to what
Also has a 18 inch diameter steering wheel which I suspect is off a tractor- makes getting in and out really tricky- is this really the size?Uploading: image.jpg…
Presume the knob under the window winder supposed to open the air vent in front? Currently blanked
Quite a few refer to ‘air conditioner’ (optimistic :blush:) which doesn’t exist so if anyone has the heater unit willing to sell
Currently the wiper works though the dash panel light switch, one unconnected pull knob on centre left below temperature control

The heater conditions the air, hence the name “air conditioner”. “Weather conditioners” which included chilled and heated air capability, as we now call air conditioners, were available in the US in the mid-1930s but widespread adoption was slow.

Gust Nelson is seeking photos of the wiring runs and connections in the engine compartment, especially along the compartment sides. At this same time his '48 dash is getting rewired. Maybe the two of you can share some photos.

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My 1938 saloon is probably pretty much the same.

The Bakelite knob below the windshield crank is indeed for the scuttle vent door.

The wiper motor switch is in the right hand wiper knob control, but it is such a Mickey Mouse design that I rigged up a toggle switch under the dash, along with another toggle switch for the carb solenoid valve.

The heater or “air conditioner” was not offered until 1940, and was optional for some years, so yours may not ever have had one.

Please ignore the hideous hole above the steering column, in which was a white plastic fan motor control for an aftermarket Delaney Gallay heater. There are two other extraneous holes in my dash from a heater temperature control and a failed attempt to install the above mentioned fan control. Somebody drilled through from the outside, drilling partly through a dashboard support nut, then found there was not enough room on the back side for the control. :sob:

Yes, the 18" wheel is correct, and without hydraulic power assist you need a big wheel.

Here is a wiring diagram for the MK IV 2.5 and 3.5, and when I rewired my 1948 1.5 litre I made a couple of sketches to help me identify locations and cable colours (these should in the main be similar to the 3.5 layout and wiring you have).


It is worth noting that the small instruments are located differently in the MkIV relative to those in the SS Jaguar. Also, the heater controls on 1.5 litre cars are swapped left for right relative to those in the 6 cylinder cars.


Photos of wiring harness runs and connections in the engine compartment.

Out of the voltage regulator and fuse box.

Along the left hand chassis rail, with takeoff to the generator.

Crossing on the chassis cross member in front of the engine.

Coming around the right hand engine mount. Note ground strap across mount.

Junction box where manette wiring joins main wiring.

Along right hand chassis rail.

Brake light switch and starter motor.

Thanks- so car may be more original than I thought!

Thanks- lovely diagrams- my car only has 3 pull switches above steering column all for lights so still not worked out where the wiper motor switch should be- may need to add one
suspect the reason I finally got my wiring loom ordered June was due to your unfortunate experience - liked the article in Jaguar enthusiasts- very detailed

The wiper motor switches are the silver “Wiper knobs” just below the windscreen on my sketch - they pull outwards to engage. I found the actual electrical contacts behind them needed cleaning before I could get mine to work and the whole mechanical linkage needed cleaning up (had rusted and seized on mine). I took the dashboard out completely to get to access - which I needed to do anyway for a full rewire and rework of the wooden dash itself.
I suspect that some owners added another “override wiper switch” - mine had an extra one just above the steering column - as the original electrical contacts behind the dash are a pain to access!!

The wiper switch is integral with the right hand wiper clutch knob. The left hand knob only serves to raise the wiper onto the screen and engage the clutch. There are two different types of wiper clutch/switch. In the early type you needed to pull the knob to disengage the clutch so that you can rotate the blade onto the screen. This had the disadvantage that the act of pulling the shaft made it difficult to get the blade to pass over the windscreen frame. In later cars the action was reversed such that you needed to push the knob to disengage the clutch. This made it easier to get the blade to pass over the frame but had the disadvantage that the clutch return spring tended to push the knob out when the wipers were parked such that the switch turned the wiper motor on despite the fact that the wipers were inactive and you had to keep giving the knob a little push now and again to switch the wiper motor off.

I strongly dislike non-standard additional switches on the dashboard so rather than adding one to get around the wiper switch nuisance I wired my wipers via the panel lamp switch. In the pre-war cars the panel lamps were independent of the main lighting switch. I think that is not true for the post war cars so you would need to revert to the pre war arrangement if you wanted to share the wiper and panel lamp functions.


I also dislike the original wiper switch set up. One has to, while driving in the rain to reach around the steering wheel, I have a push/pull switch mounted under the dash on the driver’s side of the heater. Easy to reach and not visible.

Richard, If you can’t locate an original heater you can buy a new one which is virtually the same as the original. It’s made by the same company as the original! https://www.s-v-c.co.uk/product/clayton-classic-barrel-heater-with-demist/

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If you need an original heater box Richard send me a personal message as I know someone with a spare reconditioned one.

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So probably shouldn’t look like this then!

Here are some photos for accessing the wiper switch behind the dashboard. The switch contact (on the right hand side pull knob) is not the best engineered part and needs cleaning to make a good electrical connection to make the wiper motor run. Also the mechanical parts need to be free and move easily.

Just found this drawing in my paperwork for the wiper layout.

Thanks - not been brave enough to try open the windscreen- been bolted down so need to remove these first

Talking about busses- apparently there is another mk iv owned by a mr gibbons about 7 miles from me in a village called hatcliffe near Grimsby

Seen some pictures- looks in good condition- will try make contact this weekend

Wheels at repair shop- Turrino- apparently the rust fairly superficial and down to a poor previous preparation :thinking:paint or powder coated? They seem to think powder better and longer lasting

Richard Carter

The pedant in me feels obliged to say that as well as the piping and spacers between dash and screen being trim colour, the top visible lip of the vents was paint trim colour, brush painted on those I’ve seen by the look of it.