RT142 speed signal

**Pube** · 26-02-2008, 06:06 PM

It looks like I have damaged my speedo where the speed signal is generated. In an rt142 the speed signal is generated when the internals of the speedo spin and therefore magnets turn. Outside the turning magnets there is a positive and negative terminal and some of glass circuit between these terminals. There is something in this glass cuicuit, my guess its some sort of switch that picks up the magnetic pulse as they turn and therefore switches on and off to generate an electrical pulse. My switch is stuck closed so im getting a speed signal fault from my ECU. Does anyone know what this glass switch thing is? Or am I making no scense at all? I have checked out a few local wreckers but it seems RT142's are getting a bit thin. Checked out a few other Toyota EFI dash boards of similar years but they are different. Im hoping I could get this part from somewhere like Jaycar.

**Pube** · 27-02-2008, 08:10 AM

This is the back of the speedo

This is the switch thingy im talking about

**GA61XX** · 27-02-2008, 12:03 PM

This is a Reed switch...
Used in many allarm's...
Go to Dick Smiths, Jaycar or one of the others.... $3.oo aprox...

**Pube** · 27-02-2008, 05:06 PM

Jaycar had no idea what it was, although I didnt mention its a reed switch. How do they work?

**Pube** · 27-02-2008, 05:14 PM

For fuck sake, I just found reed switches on the jaycar website. You cant get good help these days!!

**GA61XX** · 27-02-2008, 07:27 PM

Mosh allarm systems use them.. they is hidden in side those small plastic boxes on door's & windows...

it's just a glass tube with 2 x metal switch contact's.. magnet closses them..

i have a few shops here in Adelaide that have them in 4 sizes...

cheers