ST185 - ST205 engine swap

[72 TA22]

We are just about finished wiring an ST205 engine and ECU into my ST185. Can anyone give us some direction as to how to get the speedo working?

[Norbie]

Try getting in contact with JustenGT8, he put a 205 engine in his 185 some time ago.

[camrygt?]

presuming that you have an electric sender in your gearbox, just join the signal wire at the sender up to the signal wire at the gauge itself.
I think in the wiring diagrams the gauge is connected to the ecu but it will still work if it is connected directly to the sensor.

The 205 ecu will log an error code without the speed sensor connected and I think it goes into "limp mode" from this code and drops your boost back to 8psi or something. It takes a few minutes of driving for the code appear and the check light come on.

If you are having trouble finding the signal wire one is 12V the other ground and the third signal so a multimeter will find them quickly. The gauge is easy found as well the tracks on the boards at the back of the dash are usually labeled but again only three screw connections to the gauge (ground, power and signal)

went through the same putting 205 motor in camry

[72 TA22]

Camrygt, thanks for the info.

But how do you prevent the ECU error code? Is it simple as splitting the signal wire to run to both the ECU and Speedo?

[camrygt?]

yep, just join the signal from the gearbox sender to both the gauge and the speed input on the ecu.