Slash 5

In late 1969 BMW came out with a completely new, re-designed flat twin: the /5 series. BMW built the /5 model series in Berlin until 1973. The instrument gauge is a single round unit with speedo above and smaller tach below. This model has no printed circuit board like the 1974-on bikes. Each indicator light is either a small BA7 or a larger BA9 bulb in a bulb socket inserted in a socket in the back of the instrument case: all accessed inside the headlight bucket.

Several /5 Riders have asked me about led lighting for their /5 instruments. As always, the first technical difficulty is replacing the charging indicator with a led. The charging circuit requires sufficient amps to excite the alternator at start-up. Otherwise the alternator will never actually start charging the battery. We’ve solved this with a resistor cluster/dongle that is connected into your stock charging/GEN bulb socket.

HOWEVER: this is NOT a “plug and play” unit like our other KATDASH units. We are providing you with a kit that consists of the properly sized led bulbs, in the correct color for your gauges. YOU will have to dig into the snake farm of your existing 50 year old headlight bucket wiring. IF one of your lights is currently not working; you need to diagnose that. Changing from an incandescent bulb to a led bulb WILL NOT FIX any existing electrical circuit problems. The kit includes a new wiring harness for the turn indicator. That means you have to access your connector block and replace the stock wires with new ones. Disturbing any of this old stuff involves a certain amount of risk that screws will strip, connectors will break or separate and need to be replaced.

We’ve installed 4 kits, on 4 different bikes to check for fit and function. Two of the 4 bikes had no parking light bulb socket, (larger BA9 size) AND no wires to connect to the socket. Two of these parking lights also had the early style/ no socket: and simply sit on 2 small posts and fit through a hole in the reflector. In order to install a led bulb in these parking lights- you will need to file the hole in your reflector to get the bulb to fit. See our further info on this below. Two of the bikes had issues with the high beam indicator: both had the headlight bulb plug re-wired at some point, and on one bike- the high beam indicator stayed on all the time, on the other- it didn’t come on at all. Both bikes arrived in this condition- it is not a function of installing a led bulb. Two of the bikes had very bad small insulated sockets (neutral and oil lights) These small sockets are becoming NLA. (see below) Be prepared to replace damaged or corroded stuff in your headlight bucket. Working instruments, with no headlight bucket fires from old wire shorts is a good thing.

the KATDASH /5 kit:

Our kit includes led bulbs for all the instrument indicators, the turn signal indicator and the parking light in the headlight assembly. More importantly it includes a plug and play resistor dongle for the RED charge light indicator (GEN).
Your charging system is designed to use the current that passes through the larger charge light bulb filament, to sufficiently “excite” the alternator and get it to start putting out current, and charging the battery. If the bulb burns out, you will have no charging. The bulb will also light dimly or flicker if there is a current imbalance between the diode board and the battery: a GEN light that stays on continuously indicates a charging problem you need to track down.  The GEN light comes on again at idle- because the alternator is not turning fast enough to make charging current. This is the stock setup- ALL the Airheads from 1970-1995 have the same charging circuit design.

A led alone cannot pass as much current as a bulb: you must add additional resistors to increase the current flow. The charge light dongle in our kit has about 1/2 the resistance of the bulb. On initial startup (only) you will have to rev your bike a little higher to get the light to go out and the Alternator charging. After initial startup, the red indicator will operate the same as always.

5 small led bulbs: blue high beam, amber OR green neutral, amber oil, and 2- white instrument illumination
3  large led bulbs: red charging, green OR amber turn indicator, and white parking light bulb.

** replacing just these bulbs alone would cost over $37 from BMW **  Our kit also includes:

charging reistor dongle: this is a “piggyback” connector that you plug into your oem bulb socket, then plug your existing wiring harness connectors into the piggyback. Color coded wires for 12v & charging system connection.
turn signal indicator harness: the oem TI (turn indicator) has the blue w/ bk and blue w/ red wires coming into the 2 connectors on the bulb socket. A bulb will function 2-way like this, a led WILL NOT. What we’ve done is build a new wiring pair with properly colored wires and additional diodes to bring blue turn wires into the same connector, and added a brown ground wire to the other connector on the bulb for a ground. You simply disconnect your existing TI wiring pair, and install the new replacement. The bare ends of the harness are properly tinned to insert in the connector block.

NOTE: You will need to modify your 2 small, insulated BA7 sockets; neutral and oil indicators. You need to trim off the (about 2mm) top plastic rim of the insulated socket, to get the led bulb socket to insert deep enough on installation. This does not affect the function of the bulb socket in any way. You may also need to modify your stock parking light/headlight reflector assembly. (See the bottom of this page)

Here are the installation instructions for our kit FYI:   Slash 5 kit installation

Converting your /5 to LED Turn Signals

The /5, with the turn indicator in the headlight bucket has a continuous 12v loop through the stock turn indicator bulb. However with the /5, as opposed to the late RS &RT bikes, you can access just the turn indicator wiring harness separately. We have built a replacement wiring harness that includes 2 properly color coded wires with diodes to interrupt the loop circuit, along with a ground wire. You replace your existing turn indicator wiring harness, install a LED compatible flasher relay and LED turn signal bulbs. You can also install a LED turn indicator bulb, or keep the stock incandescent indicator. If you install LED bulbs in your /5 turn signals YOU MUST CHANGE THE TURN INDICATOR WIRING HARNESS!. You can build your own with diodes to control the current loop, or you can buy ours- but you cannot install LED turn signals without removing the 12v loop connection at the turn indicator.

Order your Slash 5 kits on this page

IMPORTANT:  Please note that the kits come with different colored led Turn Indicators and Neutral bulbs!  Be sure to order the matching color for your bike.!

ALL the Slash 5 kits are $49 + $11.50 shipping & handling (USA)


KATDASH Slash 5 kit: AMBER TI and GREEN neutral:

Sorry! Out of Stock


KATDASH Slash 5 kit: GREEN TI and GREEN neutral:

Sorry! Out of Stock


Want to change your turn signals to LED & not mess with your gauge?

We have a complete LED turn signal kit that includes our replacement wiring harness with 2 properly color coded wires and built in diodes to interrupt the loop circuit, along with a ground wire. You replace your existing turn indicator wiring harness, install the included LED compatible flasher relay, LED telltale (turn indicator) bulb and 4 of our bright white, waterproof 57-500 LED turn signal bulbs, that fit the reflector in your /5 Aluminum turn signal housing. Comes with installation instructions.
IMPORTANT:  Please note that the kits come with different colored led Turn Indicators!  Be sure to order the matching color for your bike!


New Telltale wiring harness, flasher relay, 4 57-500 LED bulbs & GREEN telltale/ turn indicator led.  $60.00


New Telltale wiring harness, flasher relay, 4 57-500 LED bulbs & AMBER telltale/ turn indicator led.  $60.00

More parts for your Slash 5:

2-pin Electronic Flasher Relay for /5

LED compatible flasher relay to replace your existing thermal flasher. Be sure to note the pin locations when you pull the existing relay out of it’s holder. This relay is silent- IT HAS NO CLICKING NOISE- The rate is adjustable by a screw on the bottom. You MUST replace the turn indicator harness with a diode pair & ground if you are installing led turn signal bulbs. (color may vary)

BA7 Un-insulated socket

For /5 instrument lights, high beam indicator and clock and voltmeter lights on later bikes. Single spade terminal: they ground to the metal housing they are inserted in.  $7.50 each

DeoxIT 2ml tube: DeoxIT electrical contact cleaner by Caig. This is THE stuff to use on all your electrical contacts on the bike.  

Deoxit disolves corrosion, Improves electrical contact and protects metal surfaces from new oxidation.

Comes with 2 dental brushes to clean corrosion and gunk from your female connectors, or other contact sockets. DeoxIT can, and should be used on all the electrical contacts all over your bike.

DeoxIT 2ml tube with 2 brushes: $5.00

Additional information on your /5 headlight bulbs and installation

There are 3 types of bulb sockets used in the /5 Headlight bucket:

Small 2 terminal BA7 insulated sockets- BMW part # 62 148 081 725. This socket is for the Oil and Neutral indicators. I believe that BMW has just recently discontinued this part.

However it is also a Porsche part # 999-632-009-10 and available from BA7 socket

the larger 2 terminal BA9 insulated socket- BMW part #61 148 680 131. Max BMW has them. This socket is for the GEN (charging) indicator and the Parking light. This one is currently still available.  If any of your insulated sockets are badly corroded or cracked- you should replace them now, while you can still get the part. Stoddard also has these. The porsche part # 999-632-002-00.

There is also a single terminal, un-insulated BA7 socket that is used for the instrument illumination lights, and the high beam indicator. It is also used in the later bikes for the voltmeter and clock. This part is NLA from BMW. I have found a German source and have them available here. See parts list above.


So far, I have seen 3 different parking light bulb assemblies: the stock/original headlight bulb collar (left) which is spring mounted on 3 tabs. The Parking light is under the bakelite assembly (bottom of photo) and sticks down through a round hole in the reflector.  If this is what your headlight assembly looks like: YOU WILL NEED TO MODIFY IT to get the led bulb installed. Details below.

Another assembly we found  was a modified original bulb collar with the original parking light assembly removed, and a stock BA9 insulated socket installed.

And the other option I’ve seen is the later (1974-on) bosch assembly.  If you have this headlight assembly you will need a BA9 socket to install the parking light included in this kit. These are available from Max BMW or Stoddard.

The stock bulb socket pins sit on small notched posts, (left photo) and make their ground connection to the reflector shell on these posts. (clean and deoxit all connections!) The top of the led bulb is larger than the socket, so it has to be installed from the inside-out. (Right photo) You will need to carefully file 2 notches for the socket pins to fit through. You may also need to enlarge the hole slightly for the bulb socket. Or, you can just stay with your stock arrangement.