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72 mgb Wiper switch no power source

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Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
Mitch, I considered copying my setup with the extra fuse indicated, but that would need an amalgation of Auto Advance Bentley sheets 12, 13, 15 and possibly 17 because of USA extra's.

With text mainly on just diagram nr 12 it is also possible, see the following floating fuses as identified correctly:
1) left up, below the alternator with a long line via the bottom to the hazard switch, my guess is mostly physically located under the fusebox and always live on + battery
2) shown sligthly left up from the fusebox, for the White Green to Green (Pink) feeds to all kind of parts in ignition switch position "I", hides behind the glove box IMO
3) just left of the radio and probably just part of the radio as supplied by their manufacturer for all kind of cars with a light fuse": mostly 5 Amps, later radio's may have 10 Amps

Then the extra one I found:
4) not shown here, but this is the one I mentioned before: sits between the heaterswitch and via a cable loom the connector on the stalkswitch for feeding the wiper motor (G(K)-G(K) wiring)
Another way of describing is jumping to the nr 17 diagram for 1974 cars: the bullit shown between these two points is in my case now a floating fuse, I wonder about yours eye rolling smiley
Hangs down from this switch behind the dash on a very short wire, its other end to the stalkswitch sits behind the radioconsole and enters the loom running from the right to the left

Do know if you have problems in restoring the feed the official way, you may always link the proper stalkswitch connector wire for the G(K) feed with a bypass wire to one of the combined bullitts feeding amongst others the radio. Just connecting the wire going to the radio (ahead of the 5 or 10 Amp fuse of course) to this connector point and all is well. You may also raise the fusing to 15Amps for a combined feed behind this fuse, but this is rather high for a radio (mine for just the wiper motor is 8 Amps)

PS Other malfunctions for the wiper motor assembly may come from its own connector. Once the glovebox is removed you can reach behind the assembly and draw this connector out.
Spraying it with contact fluid and putting it back often restores all functions (I even restored my HS speed by just wiggling and pushing this female type connector on the male spades)

In reply to # 3545837 by Mister Mitch Don,

Thanks...I am now going to try and find these "floating" fuses that are under the dash and behind the glovebox.....

I did check continuity from the switch to the floating fuse under the fuse box....

Mitch



Edited 1 time(s). Last edit at 2017-07-06 10:28 AM by Donthuis.

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Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
Yesterday another surprise on non-standard feeds on my 1972 USA Tourer: when checking my heater fan it was dead, although the wipers remained active and they are on the same feed. Knowing by now the existence of this extra non-standard floating fuse to my wiper circuits, I grabbed behind the radio without removing the radio this time and found the floating fuse holder I renewed a number of weeks ago back and well connected, but also felt another half of a floating fuse holder next to this one and another half hanging down from a place near to the heater fan switch eye popping smiley

This is another not documented fuse and apparently it only protects the heater fan circuit. After re-inserting the fuse I found lying on the tunnel carpet I managed to reattach both halves again with the fuse inside. This fuseholder was not broken, so this action was sufficient for restoring my fan switch circuit. In the mean time I bought some of these special 8 Amp fuses just to be sure.

For those possessing MGB's from similar build and model year: know there may be more floating fuses in this feed line than the Auto Advance /Bentley diagrams indicate!
Now next to the 17/35 Amps large glass fuses found in the fuse box and the 5Amps smaller glas one, there is a third small ceramic variety of 8Amps to be found in some unexpected places grinning smiley

PS I wonder why these extra measures were taken by the factory at the time to provide for a total of four floating fuses to seperate failures in the radio, the fan or wiper motor circuits from each other and prevent the one floating fuse which IS shown in the diagram from blowing on any of these individual failures. Why did they not continue this more extensive protection in later years? When looking at a number of the Auto Advance wiring diagrams over the years, early RBB included, nowhere did I find these extra floating fuses depicted anywhere confused smiley



Edited 1 time(s). Last edit at 2017-08-12 05:51 AM by Donthuis.

gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
i have a 72. There IS a bullet between the green/white and green pink.

It is a 4-way sited directly under the right hand wiper box (as you view from inside car).

I had the steering column, console, wipers, cold air vents - all removed and it was only possible to touch it having scraped lots of skin away.

to get any kind of tool on it, dash needs to come out. BUT - my car is a RHD.

a LHD would have similarly located connector, but the route to it will be different and perhaps simpler.

G

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Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
There are a lot of bullits in this circuit, I referred to the floating fuse between white green and green pink wiring as clearly shown in the Auto Advance diagram and the fact in my car the green pink wiring to heater fan switch and wiper motor circuits not only has bullits, but also two extra, undocumented floating fuses. These extra ones are located behind the console where the radio sits.

If your RHD car has just a bullit between white green and green pink wiring and not the documented floating fuse this is yet another change from normal practice... eye rolling smiley

PS Later cars, after 1974, had the wire color green pink to fan and wiper motors changed to plain green

In reply to # 3571767 by gray i have a 72. There IS a bullet between the green/white and green pink.

It is a 4-way sited directly under the right hand wiper box (as you view from inside car).

I had the steering column, console, wipers, cold air vents - all removed and it was only possible to touch it having scraped lots of skin away.

to get any kind of tool on it, dash needs to come out. BUT - my car is a RHD.

a LHD would have similarly located connector, but the route to it will be different and perhaps simpler.

G

gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
i do not have the extra floating fuses you mention don, just the one in the engine bay.

i meant to say, mine is a late 72, but 73 model. manufactured nov 72.

That is when the UK used to change model year - in October. "get next year's model early.."

I can hear the sales guy even now.

G

Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
Mine is from production March 1972, so modelyear 1972 as well, but in USA version. It was only brought on Belgian roads in 1973 and has non-period banjo axle, the rest seems standard Cal. USA. It says BL Belgium on the slampanel, but whether or not local (part) assembly was performed there is debatable. Anyhow wiring was not changed by the PO, he just yanked the radio and its 5 A floating fuse out. At the time these two floating fuses probably hanging from the same double bullit did not come apart, so I never investigated this any further (little did I know of these B details in 1978 confused smiley )

Next is my second holiday this year, the shorter one to Belgium next month. A working heater fan and functioning wipers may well come in handy. smiling bouncing smiley


In reply to # 3572015 by gray i do not have the extra floating fuses you mention don, just the one in the engine bay.

i meant to say, mine is a late 72, but 73 model. manufactured nov 72.

That is when the UK used to change model year - in October. "get next year's model early.."

I can hear the sales guy even now.

G

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