Since I decided to install a standalone EMS I've been looking at the schematics to make sure all of the instruments are going to continue to work when the Motronics bow is removed. The speedo has me stumped. I can find a sensor for the Tip but not the 6 spd. Can someone run down the signal source and wiring , or at least enough to get me started tracing the circuit?

 

My speedo went out when I broke the driver front wheel hub at Road America Club Race. ABS ring came apart. This makes me suspect it runs off that ABS ring/wheel sensor.

 

Speedo runs from the ABS control unit to relay (frequency control unit) then to speedo.Should work fine with standalone.

 

OK, running off the ABS was on my list of suspects but I was not able to confirm it using the schematics. I'll go back and take another look.

 

For those that are dying to know:

The ABS control unit receives wheel speed information from sensors at each of the four wheels. Among the many inputs and outputs from the ABS, Pin 17 provides a signal to Pin 6 on the FCU or Frequency Converter Unit, also known as G16, located in the Central Electrics (AKA main fuse box). FCU Pin 5 is the output signal to the speedometer. Pins 2 and 7 are power and ground respectively.

 

I'm about to buy an Eclipse head unit with a TomTom GPS built into it. It has a provision for the GPS to be hooked up to the vehicle speed sensor. Same thing as you're talking about?

 

Mike, thank you for finding and sharing that info!

 

My pleasure, Arash.

RD,

I don't know the answer to your question. We would have to know what the GPS is looking for and what the characteristics of the speedometer signal are. Unfortunately, I'm currently unable to measure the signal characteristics since my car's brain and central nervous system are hanging from hooks in my garage

 

Mike/anyone,

Where is the best point to pick this up - right from the FCU. I need a signal to interface with the Traffic Pro GPS i'm installing.

 

There is a fuse in the speedo circuit too. not sure what number but i could find it. Iy may have something to do with ABS, i can't recall, but when i bought my car, i had to remove the fuse to drive it back from memphis. it was causing shuddering under high speed braking, so it was likely the ABS control unit. As it turned out the POs indy had put wrong rotors on the car. he was told it was a 2k part that was bad. it was just the rotors being wrong size.