The Snakes Alive CMP Wiring Project

[Jacques Reed]

Hi Hanno,

Just had a look again at the back of the Ford Cluster. I think the brass bridge between the ammeter and the Oil pressure gauge should not be there. That is used with a battery indicator type gauge to supply power to all the gauges when the ignition switch is thrown.

Will have a look at the wiring again later today and make up a revised Ammeter equipped wiring diagram at the instrument panel using Mariano Paz's great information on the late war wiring plate.

Cheers,

[Jacques Reed]

Hi Hanno,

Here is a revised wiring diagram showing the differences in red between a Battery indicator gauge equipped instrument cluster and an ammeter equipped one.

Not a lot required to change over to an ammeter from what I can see. Mainly the routing of the supply from the solenoid to the Battery terminal on the regulator.

Original Regulator Battery terminal to Ignition switch wire can stay even though Mariano's diagram takes current from the Ammeter to the Ignition switch. Same thing electrically however.

Only one Brass bus strip used, too, from Fuel to Temp gauges. If ammeter to Oil pressure gauges had a bus strip all gauges would be "Hot" all the time. They should be only be energised when Ignition switch is thrown.

Thanks again to Mariano Paz's excellent late war wiring plate photos. Makes it so easy to trace wires compared to the rudimentary Ford Manual schematics.

Fairly happy with it all but always glad for "peer review" as they say. It can be easy to miss things.

Cheers,

CMP wiring 1943 schematic.jpg

[Hanno Spoelstra]

Originally Posted by Jacques Reed

Just had a look again at the back of the Ford Cluster. I think the brass bridge between the ammeter and the Oil pressure gauge should not be there. That is used with a battery indicator type gauge to supply power to all the gauges when the ignition switch is thrown.

Thanks Jacques. I've always thought that my BATT meter did not do much, I now found it has a live feed (bridged to the oil pressure gauge), but no wire to ground - see photo. This makes me wonder why it was moving at all? Will add a ground wire and see how it behaves.

IMG_7907_redlined.jpg

PS: the white terminal block will be removed. I noted this loose yellow & red wire dangling under the dash and it turned out to be live. Using the diagrams on here I found this is the feed to the inspection lamp socket. This socket was removed in the past to make way for a traffic indicator switch.

Will have a look at the wiring again later today and make up a revised Ammeter equipped wiring diagram at the instrument panel using Mariano Paz's great information on the late war wiring plate.

Will look at that in detail later. I am trying to get a better understanding of my F15A's wiring, making it work better and meanwhile draft the specs for the new loom I want to order.

I may switch from the BATT to AMP meter, though I plan to use an electronic regulator. I've just replaced the indicator/ flasher relay by an electronic one, and it is a huge improvement because it uses far less power and it is independent of load. I am becoming a fan of modern electronics. I recently fitted an electronic distributor, quite an improvement so I plan to add more in an effort to improve drivability and reliability.

[Jacques Reed]

Hi Hanno,

Just looking at your picture there should be a wire, 30A, a jump from the oil pressure gauge brass bus to the Temperature gauge brass bus to supply current to the Battery and Oil Pressure gauges when the ignition switch is thrown.
There should be wire, 30, from the ignition switch to the Temperature gauge brass bus to supply current to the Temperature and Fuel gauges and then to the other gauges via 30A.

The wire into the Battery indicator is my concern. If it shows voltage only when the ignition switch is thrown then it is wire 30 and can be connected to the brass bus at any gauge to supply them with current. Diagram shows the Temp gauge but any brass bus is the same electrically.

If for some reason that wire into the Battery indicator shows voltage continuously it could be coming directly from the Battery via the regulator and therefore your wiring is setup for an ammeter. If that is the case it could cause a serious problem to the wiring and gauges if the Battery indicator is sent to earth. A quick check will determine if that wire is "hot" only when the ignition switch is on and therefore set up for a Battery indicator.

I have found with numerous owners over the years and many jury rigged wires on these vehicles it is best to check and double check. My first truck had many disconnected wires and even house wiring used in some places!

Cheers

[Hanno Spoelstra]

Originally Posted by Jacques Reed

Just looking at your picture there should be a wire, 30A, a jump from the oil pressure gauge brass bus to the Temperature gauge brass bus to supply current to the Battery and Oil Pressure gauges when the ignition switch is thrown.
There should be wire, 30, from the ignition switch to the Temperature gauge brass bus to supply current to the Temperature and Fuel gauges and then to the other gauges via 30A.

The wire into the Battery indicator is my concern. If it shows voltage only when the ignition switch is thrown then it is wire 30 and can be connected to the brass bus at any gauge to supply them with current. Diagram shows the Temp gauge but any brass bus is the same electrically.

If for some reason that wire into the Battery indicator shows voltage continuously it could be coming directly from the Battery via the regulator and therefore your wiring is setup for an ammeter. If that is the case it could cause a serious problem to the wiring and gauges if the Battery indicator is sent to earth. A quick check will determine if that wire is "hot" only when the ignition switch is on and therefore set up for a Battery indicator.

I have found with numerous owners over the years and many jury rigged wires on these vehicles it is best to check and double check. My first truck had many disconnected wires and even house wiring used in some places!

Hello Jacques, thanks for your guidance.

Currently the dash on my F15A is wired as follows:

• Live feed from ignition switch to BATT, strip connector to OIL pressure, then a wire runs (hence the double wire in the connector) from BATT to TEMP with a strip connector to FUEL.

I checked and the instruments are "hot" only when the ignition switch is in the on position. I have temporarily grounded the BATT meter (see the blue connector) and when the engine is running it slowly creeps up. Have yet to take it for a test drive to see if it is in the green at driving speeds.

IMG_7927.jpg

Indeed previous owners have fiddled with the wiring, hence my actions now to go through it, understand and correct it. It does not help the original covering has faded to a level where the colours are very hard to discern. Hence a rewire is scheduled for this winter.

For the upcoming event this weekend I have proper working indicators again, over the years they became dimmer and dimmer, with the old mechanical flasher relay, dash indicator light and bad connections robbing away 1.5 V from the 6 V available. With the connections cleaned up, dash indicator light omitted and an electronic flasher relay I now have the full 6 V supply to the indicator lights.

IMG_7930.jpg

[Ganmain Tony]

Where is the other end of your battery gauge ground wire connected Hanno?

[Hanno Spoelstra]

Originally Posted by Ganmain Tony

Where is the other end of your battery gauge ground wire connected Hanno?

Tony, my F15A has a ground stud under the dash, just above the steering column. That’s where I’ve grounded the flasher relay and the BATT gauge.

0F056C02-E497-4D55-8148-3EA3C9306F91.jpeg

[Ganmain Tony]

Thanks Hanno.
I will probably do something similar so it's good to see what other set ups look like.
Great to see your truck, nice example of an F15A.