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Time To Activation
___ ___ ___ test tests the heater by measuring the time it takes for the sensor to start operating.
Internal Resistance, Down
TTA test measures the time it takes for the sensors ___ ___ to decrease enough to pull ___ the signals bias voltage, quicker drop means better heater operation.
If the heater circuit doesn't work then the internal sensor resistance will stay ___ and cause a slow response or for the signal to stay at the ___ voltage
Bias Signal, 0V, Exhaust Gas
When the sensor first heats up the 450mV ___ ___ will drop towards ___. If the drop is gradual and long means the ___ ___ is slowly heating it up and not the sensor heater.
Disconnect, High Impedance
Integrity test: ___ sensor connector and read the O2 signal on scan data to see if it goes to its bias line. Remember our DVM can cause a small drop in signal voltage as it pulls down the weak signal through its ___ ___ resistor
Resistance, Up, Down
Check computer response and CI using our bodies ___ to pull ___ or ___ the signal line with the sensor disconnected. Looking at scan data for rich or lean condition
Current flow through our bodies is less then ___ but can transmit around 7v. Amps are ___ so we won't harm our computer with these low levels.
Voltmeter, Current Flow, Test Light
Voltage sensing circuit in an ECU is high impedance like a ___ and allows only negligible ___ ___, this means we can use our ___ ___ or our bodies resistance to check circuit bias response as this will not harm our ECU.
Zirconia O2 bias signal lines can vary from 450mV to ___ for Peugeots or even ___ for GM vehicles.
If the sensor ___ is working then the bias voltage should drop rapidly within ___ seconds
Current, Capacity, DVM
Bias signals may use the common 5v reference but it will be sent via a large resistor to weaken its ___ carrying ___ making it very sensitive and reactive to even a ___
A quick test for heater operation is if our permenant ground rises to ___ from 0V with KOER, assuming standard wiring this pull up shows that around ___ amps is being draw through the circuit.
Signal, Response, Heater
O2 heater faults can cause ___ DTCs (due to slow or no ___ ) O2 signal faults can cause ___ DTCs codes (fails the Time to Activity test as the bias signal doesn’t drop).
Some models may ___ the heater operation to allow any ___ to burn off slowly by exhaust gas
Rich, Active, Heat, Open
The sensor signal will always fall towards 0V first, even in ___ conditions. As it has to become ___ first through ___. As the sensor ciruit is initially ___ and then through heat the resistance lowers pulling down the bias.
The computer doesn't always update the signals to scan data with ___. Sometimes the ___ signal is needed to activate the computer to look at the sensors.
Newer systems can use a bias on the ___ aswell to eliminate ___ (engine block noise)
Bias, 2.5, 3.5
If a sensor has ___ ground at 2.5v then expect the O2 sensor to oscillate between ___V - ___V
Actuators, Reference Low,
There is a lot of block noise at 0v due to ___ etc, by moving the sensor ground it can reduce this interferance and is labelled as ___ ___ in wiring diagrams.