this is in reference to the linked thread:
http://datsun1200.com/modules/newbb/v ... e=&topic_id=26205&forum=1

- I have multiple dash pods, 2 of which have this item & the one I'm putting in the dash does not - does it matter at all?

I also noticed 2 posts on the pods where the tach / clock yellow wire would connect & the earlier pod (out of the 73) only has one (72 pod going in dash).

do I need to do anything or be concerned, it didn't seem an answer was had from the attached thread.

Thanks, E

so I'm going to assume no one knows what this this does do to the lack of response. That must mean I just dont need it! Guess we'll find out.

Hi evan,

the other thread has this photo:



The box in the photo is the 10mph speed sensor. Yes, it is needed for correct operating of the emission control system on the 1973 model. Australia 1200s used this kind of switch after 1978.
* 25035-H7000 ASSY-AMPLIFIER SPEED SWITCH


Be aware that 1973 wiring is significantly different, even though it looks the same. I'm not sure if using a 72 wiring harness in a 1973 will burn anything out, but I seem to recall that the headlights are wired contrarily (negative switched instead of positive switched) plus the usual minor differences.

well lets hope not as I'm using the 72 dash loom due to the 73 one being the subject of prior hackery. Somebody did a number on the loom before me & its pretty unusable but the 73 was perfect, as was the 72 dash pod which is why its in there instead of the 73.

I'm now wondering if the red wire I just posted about has anything to do with this amplifier switch in a 73? Maybe like the tach leads its all there to start with???

Didn't that thread say as well though it had to do with a 4spd trans & speedo calibration or did I misread it?

The thread was asking what it was, and people having different ideas. Since 2007 we now know what it is, it is the speedometer speed sensor for cutting spark advance.

If you use the 1973 USA dash harness in a 1972 car, I would check th headlight wiring before connecting the switch. Or at lease make sure you have the fusible link installed.

Thanks Dave, would the circuit path be different from 72 to 73 for the headlights?

Made an error - I'm using the 72 dash loom, frame, faceplate & gauge set going into the 73 car. The 73 dash assembly is pretty well trashed so really the only connections will be to the main harness which I've not done yet so I'm not sure if there are differences between the harnesses for 72 & 73 years of vehicles.

I did actually compare the circuit paths on the backs of the 72 & 73 dash pods & there are a bit different but all circuits still serve the same functions - slightly different layout & one extra + post by the yellow tach connection.

Yes, 1972 and 1973 harnesses are different, both the dash harness and the engine harness and the body harness. Shouldn't cause any harm except for the headlights -- somebody said they were negative switched for 1973 just like the Datsun 510. I don't know if that is true.

1972 models have this solenoid wired to IGN, 1973 m/t has it going through the switch.


See Speedometer section Amplifier Speed Switch