MSS54 - ADC converter (coolant temperature error)

[Tomba]

Dear All,

I have a MSS54 ECU which reads incorrect coolant temperature. As a consequence the engine runs to rich. I suspect it has some component blown up. Maybe the ADC converter is bad. I wonder if this ECU uses a separate one or internally in the CPU. Who knows? Does somebody maybe has diagrams of the circuit board or photos with component names?

BR, Tomba

[sapote]

Dear All,

I have a MSS54 ECU which reads incorrect coolant temperature. As a consequence the engine runs to rich. I suspect it has some component blown up. Maybe the ADC converter is bad. I wonder if this ECU uses a separate one or internally in the CPU. Who knows? Does somebody maybe has diagrams of the circuit board or photos with component names?

BR, Tomba

This CPU has many internal ADC channels so no reason for it to use an external ADC.
How do you know if the wrong data is not due to the voltage at the sensor wire but the ADC itself?

[Tomba]

This CPU has many internal ADC channels so no reason for it to use an external ADC.
How do you know if the wrong data is not due to the voltage at the sensor wire but the ADC itself?

Swapped ECU and no errors anymore (same flash content).
Who knows a resistor is damaged... still need to look carefully.

[sapote]

I’m sure the Tstat signal is not directly connected to the cpu pin, but there’s a signal condition (resistors, caps, amplifier) and voltage limiter before connecting to the pin.