Is it ECU controlled?......

[pirate_texxx]

ive been curious about the HUD in the s13. after searching and looking at 8 pages of threads that contained the letters HUD im still sorta lost.

the HUD gets its info straight from the cluster correct? or does it receive its info from the ECU?

[koukimonster139]

HUD gets info from the speedo in the actual cluster, which comes from the ECU, so technically, yes.

[projectRDM]

No. The VSS sends the signal to the cluster first, then to the ECU, ASCD, and ATC.

Th HUD unit piggybacks the same signal from the cluster. The ECU doesn't see it until after the signal is converted to drive the gauge.

[g6civcx]

No. The VSS sends the signal to the cluster first, then to the ECU, ASCD, and ATC.

Th HUD unit piggybacks the same signal from the cluster. The ECU doesn't see it until after the signal is converted to drive the gauge.

This is correct. The VSS pulse needs to be converted to a digital signal. If you fed the VSS signal straight to the ECU the ECU will not know what to do.

The speedometer acts as a digital signal converter before the VSS signal is sent to the ECU. HUD or needle, both function the same.

This setup is the same on a lot of cars. Some cars use a buffer box of some sort before feeding the VSS signal to the ECU.

[pirate_texxx]

i appreciate it, basically i was trying to figure out if swapping ECUs would mess up HUD in any way, but now i know the answer is no.