Adding a shift light

 

I was just back from holidays, but couldn't stay put on that extra day off before the week-end

Kelvin on the Caterham Suzuki Owners (160, 170 and SS600) Facebook group just shared how he added a shift light with very little tinkering.  And actually no change to the car loom, as the required wire is already there, waiting for us.

The Caterham 170R is factory fitted with a shift light between the speedometer and tachometer. Us plebeians owners of the 170S flavor enjoy a seatbelt warning light instead.

In my case that seatbelt light has never been lit, because the car has never had any seatbelt : only 4 points harnesses that are not connected to the wire left dangling on the floor near the driver seat.

Behind the hole are 3 small female spade connectors :

1. A connector with 2 green wires, that provides +12V when ignition is on
2. A connector with 2 black wires, providing ground through the switch in the seatbelt buckle
   
3. A connector with a single green+purple wire, that provides ground from the ECU when the engine reaches 6800 RPM   (my rev limiter is set at 7000 RPM)
    

Getting a shift-light is as easy as moving the black wire of the seatbelt light from the black connector to the green and purple one. Done.

Exept that this light is way too dim to be seen in broad daylight.

Caterham offers a dedicated shift light with reference 3AGD0001B, the picture shows it's build by APEM.
It has a 14mm diameter. It's actually part of their Q14 series. But it's the dimmest one, built for indoor control panels.

I've opted for the ultra bright version in green, designed for use on outdoor control panels, visible under direct sunlight. APEM reference Q14P1BXXHG12E.

With my hands in the way most of the time, and being focused on the road anyway... I've added a 12V buzzer. You cannot miss the shift-light signal when it turns on, and it turns on each time you turn the key, very un-subtle.

The new LED indicator had no wiring, it had to be done at home. The buzzer goes through the 14mm hole and nut after the pair of spade connectors have been through first. 

The loom is secured by on wire tie.

Below, first third of the image, center : 3 single wire spade white connectors, from left to right :

• black+black, ground coming from the seatbelt (not used)
• green+green, after contact +12V supply (connected to the red wire of the light)
• green+purple, active low signal triggered at 6800rpm (connected to the black wire of the light)

 

(the original seatbelt light ON and not really visible)

(speedometer out)

(seatbelt warning light vs shift light as provided by Caterham, but green instead of red)
+added 12V buzzer, all goes in the 14mm nut and hole, one at a time, no issue

(final result)

(how to do it without removing the speedo, hanging from the roll-bar like a bat, trapezist-style)