Scan Tool Diagnosis

for this exercise i let the engine run at idle

the engine was a 1ZZ-FE

i plugged the diagnosis plug into the engine diagnosis port, answered all the questions about the engine details and then recorded my data

below is a table of live data from the engine

Type of information	Letters to describe	Value of data	units
how much air comes in	MAF	2.55	Gm/s
Engine RPM	engine speed	700	RPM
Throttle angle	TPS	11	%
Engine coolant temperature	ECT	73	C°
intake air temperature	IAT	22	C°
Fuel injection opening pulse	injector pulse time	2.7	ms
transmission select position	shift	4
vehicle speed	0	0	km/h
oxygen sensor	O2	0.79	V
fuel trim	short term fuel trim	-20.3	%
idle control	IAC	37.5	%
power steering condition	pwr steering	NA
air conditioning condition	air con	NA
malfunction indicator light	engine warning light	on	on

HTML Tables

my lecturer then put a fault in the engine and i looked the codes up in the scan tool.

code number - P0120
System affected - TPS
Condition described - circuit malfunction

i then checked the parameter identification

the value of data was 0%

i then did a visual inspection of the sensor to see if there was anything visually wrong with it

i did this by checking the wires and making sure the voltages were correct readings

after checking the ground wire and output to ecu, i found that the reference voltage was out of spec. i checked this by checking the voltage coming out of the ecu for the 5v reference and found out that it was not reading 5 volts

i then cleared the codes using the scan tool, i then turned the key off and then back on and found that the codes had been cleared.

a scan tool is useful because it tells you where to look for the problem on the engine, however you still need to know how to fault find on the component.