Post by
Q45tech »
https://forums.nicoclub.com/q45tech-u112.html
Tue Jul 15, 2003 7:51 am
All 55 means is te sensors are connected and they are providing some kind of a signal [they are not shorted or open]........whether it is absolutely correct must be determined by a consult reading.
For example the coolant temperature sensor could be reading 20-50F in error but as long as the coolant number rise for 2 minutes after a start it is deemed ok.The CAS [timing advance could be misset] the ecu uses this as the master clock and times everything correctly or in error +- 20 degees by where you set the CAS. The TPS provides a voltage of 0.3-0.5 volts when the throttle is closed as long as there is more than 0.2volts it is deemed ok not correct but ok.........etc, etc.
The OBD1 ecu were not very smart.