Air head indicators

Post your post 1970 technical queries here

Moderator: Moderators

jackdog
Club Member 12
Posts: 11
Joined: Mon Nov 30, 2015 5:58 pm
Country of Residence: Gainsborough, UK

Air head indicators

Postby jackdog » Tue Nov 14, 2017 4:31 pm

Hi Folks, A problem with my 1980 R100 RS indicators; The manual wiring diagram says for this particular year it should have a flasher relay with 4 terminals, mine has a relay with 3 terminals and it is a 6 volt one at that. OK so far? The problem is that the flash interval is wrong in that the indicators are lit for too long for each flash, the off interval is very short. It still passes an MOT so not really a problem you might say. I have fitted a S/H relay from a 1981 boxer with 3 terminals thinking 12volt so should flash at the correct rate. It did but the repeater on the instrument panel did not flash. Tried all wiring permutations to no effect. So sent off for a new Hella relay with the 4 correct terminal numbers as corresponding with the manual, still no joy. Flashed OK but not the repeater. So put the 6 volt one back on, everything flashes including the repeater, but at the wrong rate.
So my question is; is the 78 to 80 R100 RS flasher unit so specific to that years model ? Does anyone know of dodge to get around the problem?
A cheap looking 3 terminal 6 volt relay does, nearly, what an expensive 4 terminal 12 volt relay should do. Any clues anyone? Thanks for reading.

User avatar
Galactic Greyhound
Moderator/Club Member
Posts: 7751
Joined: Sat Aug 28, 2010 11:26 pm
Country of Residence: Scotland
Location: Dumfries

Re: Air head indicators

Postby Galactic Greyhound » Tue Nov 14, 2017 6:07 pm

Hi jackdog,

Have you got a Haynes or Clymer showing the Wiring Diagram?

If so, the Haynes wiring diagram shows a 4-terminal Flasher Relay with terminals as follows:

31 - Earth connection [Brown wire].
49 - Fused +12v supply from the TOP 8A fuse in the Headlight shell [Green/Black wire].
49a - Flashing +12v to Indicator Switch [Green/Yellow wire].
KBL - Flashing +12v to an earth-connected Repeater Light in Instrument Cluster [Black/White wire].

A 6v Flasher Relay is NOT suitable as the flash rate will be incorrect as you have found.

I'm wondering why your Hella Flasher Relay did not work - it needs to have the 4-terminal configuration as above.
If it has and your Repeater Light did not work, is the Repeater Light bulb/wiring OK? - It would seem to be if the 6v Flasher Unit causes it to illuminate but you can test this Repeater Light and wiring by disconnecting the Black/White KBL wire from the Flasher Relay and connecting +12v to this wire - the Repeater Light should illuminate if the bulb/wiring is OK.
It may be that the Hella Relay Repeater Light terminal is putting out a flashing earth (-12v) instead of a flashing +12v. If this is the case then you have the wrong type of Hella Relay to work your earth-connected Repeater Light in the Instrument Cluster.


The 1981 Boxer 3-terminal Flasher Relay (like on an R100RT), does NOT have the KBL Repeater Light terminal.
What is done here to provide a Repeater Light is to connect the Repeater Light in the Instrument Cluster directly ACROSS the LH and the RH Indicator Circuit at the connector for the Rear Lights.
This method uses the two (Front & Rear) non-operated Indicator Bulbs as a low resistance earth return for the Repeater Light so works whether LH or RH Turn is selected.
i.e.
Select LH turn: LH Turn Flashing +12v applied to one side of the Repeater Light, earth applied to the other side via the Front & Rear RH Indicator bulbs.
Select RH turn: RH Turn Flashing +12v applied to one side of the Repeater Light, earth applied to the other side via the Front & Rear LH Indicator bulbs.


This 3-terminal Flasher Relay will work for your 1980 R100RS if you alter the wiring to the same as that of the 1981 models but you would have to open up the Instrument Cluster to do so and disconnect the earth wire currently going to the Repeater Light bulb holder inside the Cluster.
This is likely a printed circuit track connection for the bulb holder so the track should be cut at a point clear of the holder (so as to keep the holder connection) and the new connection made to the track going to the holder.

You would then need to run a Blue/Black wire from the Repeater Light Bulb holder new connection to a spare terminal on the Instrument cluster side of the connector-half (likely pin #9 or #11) and then run a 0.75mm Blue/Black wire from the Main Loom side of the connector-half to the RH Indicator circuit either in the Headlamp Connector Block (L & R terminals) or on the Rear Light Connector.

The existing KBL Black/White wire from the Flasher Relay going to the Instrument Cluster pin #5 should be connected to the LH Indicator circuit either in the Headlamp Connector Block or on the Rear Light Connector.

ALTERNATIVE 1: To keep your 1980 Instrument Cluster as standard and allow the use of the 1981 Boxer 3-pin Flasher Relay, the following diagram shows how this can be done.
[This diagram also allows for the use of LED Indicators if the Flasher Relay is changed to a 'No Load' type.]
NOTE that you will NOT have the existing Blue/Black and Blue/Red Indicator wiring as shown in the diagram for your 1980 R100RS - what you have is a Black/White wire going to the Instrument Cluster Block pin #5 and one side of the Repeater Light bulb holder earthed inside the Instrument Cluster - you can cut this Black/White wire and join it to the two Diode Cathodes (k) as shown by the Blue/Red wire in the diagram - your Repeater bulb is already earthed in the Instrument Cluster so you don't need to bother with the blue/Black earthed wire in the diagram.
You will then need to run a Blue/Black and a Blue/Red wire to the Diode Anodes as shown from the LH and RH Indicator circuits.
Note that the Connector Block inside the headlamp has two terminals marked 'L' and 'R' which are the LH and RH Indicator Circuits making connection to them easy:

Click to Enlarge/Save As
R80RT LED Indicators Repeater Light Modification.jpg


ALTERNATIVE 2:
To avoid having to modify your 1980 Instrument Cluster or fit Diodes, why not fit a separate Indicator Repeater Warning Light and wire that across the LH and RH Indicator circuits - you will need a 12v bulb of around 3 or 5 W for this.
Note that the Connector Block inside the headlamp has two terminals marked 'L' and 'R' which are the LH and RH Indicator Circuits making connection to them easy especially if the new Warning Light is fitted into or near the Headlight shell.

The following is a good link for all things electrical for your bike - try and stick to the original wiring colours when adding additional wiring as it makes future faulting easier:

http://www.vehicle-wiring-products.eu/s ... 6f6c13773b
You do not have the required permissions to view the files attached to this post.
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" onclick="window.open(this.href);return false; - It works!

PhilO
Forum User
Posts: 504
Joined: Mon Apr 30, 2007 11:07 pm
Location: Tyneside

Re: Air head indicators

Postby PhilO » Tue Nov 14, 2017 10:17 pm

Hi Ced,
This is a brilliant missive. I have bookmarked it. It's bound to come in handy.
Cheers,
PhilO

User avatar
Galactic Greyhound
Moderator/Club Member
Posts: 7751
Joined: Sat Aug 28, 2010 11:26 pm
Country of Residence: Scotland
Location: Dumfries

Re: Air head indicators

Postby Galactic Greyhound » Tue Nov 14, 2017 11:19 pm

Ha ha - thanks Phil - a wee dram when replying to posts works wonders! :lol:
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" onclick="window.open(this.href);return false; - It works!


Return to “Airhead Q&A's”

Who is online

Users browsing this forum: takemineanywhere and 11 guests