AT 261 - Chapter 8 Sensors, Inputs, and Scan tools (part 1)
Name: ______
Date: ______
OBD I, Code Retrieval - Ford EEIC IV KOEO Self Test - Intermittent Faults, and Continuous Codes
Tools you will need:
Paper Clip – Special Tool PC 101
Test Lamp
Mercury Sable
Mitchell's On Demand
CODE TYPES AND FORMATS - TYPES OF CODES
HARD FAULTS (Continuous Codes)
Hard faults are problems that the computer has located RIGHT NOW. Examples are a sensor out of range or a broken wire (open circuit).
Hard faults are the FIRST set of slow codes output in a Key On Engine Off test. BEFORE the SEPARATOR pulse.
SEPARATOR PULSE
The separator pulse is a single pulse that indicates the END of hard fault codes and the BEGINNING of memory codes. It will show up as a code 10 on most digital testers.
MEMORY CODES (Intermittent Codes)
Memory codes are problems that the computer has noticed in the past. If for example there was a loose wire to a solenoid that only lost contact while driving but was making contact while testing the system there would be NO HARD FAULT CODE. The code would show up IN MEMORY. The same would happen for a sensor that only went out of range occasionally. Memory codes come out AFTER the separator pulse. MEMORY CODES ARE STORED IN KAM!
NOTE: The computer will erase the memory after a certain number of engine re-starts if the problem does not repeat itself. The number of re-starts varies from 20 to 80 depending on the year of the vehicle. The later models keep memory longer.
CODE FORMATS
Codes are output as a series of pulses. The following charts show the (approximate) timing of the various code pulses.
NOTE: Two digit codes are shown. Three digit codes have similar timing. It just takes a little practice to distinguish between two and three digit types.
HOOKUP
See figure below. EEC IV vehicles have two connectors for self-testing the system. They are located on the firewall or the left or right front fender. The large connector contains the self-test output (STO) and ground (SIG RTN). The small pigtail is the self-test input (STI).
KEY ON ENGINE OFF (KOEO) TEST
o Hook up the scan tool.
o Tell the scan tool what year/make/model and engine size you are working on.
o Select “ENGINE”
o Select “KOEO”
o Select “SLOW CODES”
o Follow the tester directions:
o When the tester is complete – exit out, and then go to “REVIEW CODES”
What are the codes you received? ______
o Remove the scan tool, and now use the paperclip and test light method.
o Turn ignition off and wait 10 seconds for system to shut off. Make sure A/C is off and transmission is in Park (automatic) or Neutral (manual).
o Hook up light and jumper (or a tester if you have one). Turn key to ON (do not start engine).
NOTE: Unhook self test input jumper (or tester if used) at any time during code output to erase memory.
o Read hard faults. ______
o Separator Pulse. ______
o Read memory codes. ______
Note - Parts of this text and graphics taken from http://www.dalidesign.com/hbook/eectest.html - 03/31/03
ALWAYS REMEMBER! FIX THE FIRST CODE FIRST!
Using an OBD II Scan Tool, Codes and Sensors - Intermittent Faults, and Continuous Codes
Tools you will need:
OTC Genisys Scan Tool
2001 Honda Accord , 1997 Acura 2.2 CL or 1997 (White) Ford Escort
o Turn the vehicle to the "ON" position (DO NOT START THE VEHICLE!)
o Verify the operation of the check engine lamp (MIL), it should come on when the vehicle is turned on, then it should go back out after a few seconds. If it does NOT go out - Get Mr. Reed
Note: A MIL that is on indicates that the PCM has detected a fault, and has either a stored trouble code, or a current problem. A MIL that does NOT come on when the vehicle is first turned "on" is a sign of a blown bulb, or someone has tampered with the MIL.
o Locate the DLC (Data Link Connector)
Note: OBDII - Stand for On Board Diagnostics II. OBD II was started in 1996 as a federal law that created a standard connector for vehicle diagnostics as well as terms, and communications protocols for scan tools and diagnostic equipment. The law states that the connector must be under the dash, within 300 mm (about 1 foot) off of the centerline of the steering wheel.
o Connect the scan tool to the DLC
o On the scan tool, select "Scan Diagnostics" then “Global OBD I”I from the scan tool.
o Press "OK" at the "All system readiness tests may not be supported"
o Select “ENTER” At the “Quick Tests Screen” and then select "Datastream 1” and then “ENGINE”
Note: Datastream "shows" what the "processor sees" to the tech. It is in "real time".
o Write down the data that is shown on the scan tool.
Name / Amount / ScaleEngine RPM / 0 / RPM
Throttle Position
Engine Coolant Temp
O2 Sensor 1/1 Volts
Vehicle Speed
Spark Advance
Absolute Load Value
Accel Pedal Pos F
Amb Air Temperature
Barro Pressure
Calc Engine Load
DTC’s Set
Long Term FT Bank 1
Malfunction Ind Lamp
Man Absolute Press
Short Term FT Bank 1
A> Setting Codes, and Gathering Clues
For each sensor - highlight the sensor and press the GRAPH button for a visual graph of the sensor
o What is the reading for the TP sensor ______%. (Norm.)
o Depress the throttle to WOT
o What is the reading for the TP sensor @ WOT ______%.
o Disconnect the TP sensor
o Now, what is the reading with the TP sensor disconnected ______%. (Disc.)
o Reconnect the TP sensor
o What is the reading for the MAP sensor ______HG (Norm.) (Escort - Pull MAF)
o Disconnect the MAP sensor (Escort - Pull MAF)
o Now, what is the reading with the MAP sensor disconnected ______HG (Disc.)
o Reconnect the MAP sensor
o What is the reading for the ECT sensor ______Deg F (Norm.)
o Disconnect the ECT sensor
o Now, what is the reading with the ECT sensor disconnected ______Deg F (Disc.)
o Reconnect the ECT sensor
o What is the reading for the IAT sensor ______Deg F (Norm.)
o Disconnect the IAT sensor
o Now, what is the reading with the IAT sensor disconnected ______Deg F (Disc.)
o Using a jumper wire, short the two pins of the IAT harness together.
o Now, what is the reading for the IAT sensor ______Deg F (Short)
o Reconnect the IAT sensor
o Look at the following on the scan tool. Record the following information.
MIL ______
DTCs ______
o Is the check engine lamp on? ______
Note: The check engine lamp should be on now. This is because you "played" with the sensors and the PCM saw a problem. MIL should be "On", and there should be at least 1 DTC in the PCMs memory. This represents an intermittent fault.
o Press Exit TWICE on the scan tool. This will take you back to the previous menu.
Sensor Facts - MAP - "Why is it at 30" Hg when the car is off?" - Because it is an inverted scale of pressure. When the vehicle is running it would (and should) show about 9-7 "HG. In other words 30" of HG on the Scan tool is WOT (0" on the gauge) - and 9" on the scan tool is really 21" Hg. (9-30 = 21). I have no idea why this scan tool shows the vacuum like this - but it does.
Facts - are IAT and ECT working? Since IAT and ECT are the same type sensor - they should show about the same voltage value on a COLD engine. In other words if the car sat out all night and ECT shows 200 and IAT shows 30 you would quickly tell that ECT is wrong. Likewise if IAT shows 90 and its only 40 out a cold ECT should show that IAT is wrong.
B> Reading Codes
Now that we caused some DTCs - Let's Go read them!
o Select "Diagnostic Trouble Codes" then "Read Codes"
What is the code(s) present in the PCMs memory? ______
What is the generic explanation of the code(s). ______
______
o Press Exit ONCE on the scan tool. This will take you back to the previous menu.
C> Clearing Codes
o Select "Clear Codes"
Clear the Codes.
Did the check engine lamp go out? ______
o Turn off the vehicle. Wait 10 Seconds
Note: The 10 seconds allows the vehicle PCM to reset. Failing to wait 10 seconds may cause the codes not to clear!
o Disconnect the scan tool, and reboot the scan tool.
o Turn on the ignition key.
D> Verify Repair
o Did the MIL come on and then go out? ______
o Start the vehicle
o How does it run? ______
o Is the MIL on? ______
PART 2 -
Continuous Code or Fault
A> Setting The Code
o Disconnect the TP sensor.
o Turn on the ignition key.
o Did the MIL come on and then go out? ______
o Start and RUN the vehicle for at least 2 min..
o How does it run?
o Is the MIL on?
o Turn the vehicle OFF. Wait 10 seconds.
o Turn the vehicle ON. DO NOT START THE VEHICLE!
Note: The check engine lamp should be on now. This is because you "played" with the sensors and the PCM saw a problem. MIL should be "On", and there should be at least 1 DTC in the PCMs memory. This represents a continuous fault.
B> Reading The Code
o Hook up the scan tool, and access the OBDII menu.
o Select "Read Codes"
What is the code(s) present in the PCMs memory? ______
What is the generic explanation of the code(s). ______
______
o Press Exit ONCE on the scan tool. This will take you back to the previous menu.
Note: If desired you can also look back at the data stream and "see" what the PCM "sees" is happening with the MAP sensor. It is very useful to look at sensors once a code has occurred. It is KEY TO WRITE DOWN READ CODES! THESE ARE CLUES! SOME IDIOTS JUST CLEAR THEM! IT’S LIKE CLEANING UP THE CRIME SCENE!
C> Clearing The Code
o Select "Clear Codes"
Clear the Codes.
Did the check engine lamp go out? ______
o Turn the vehicle OFF. Wait 10 seconds.
D> Setting The Code (again)
o Turn on the ignition key.
o Did the MIL come on and then go out? ______
o Start the vehicle
o How does it run? ______
o Is the MIL on? ______
E> Reading The Code (again)
o Hook up the scan tool, and access the OBDII menu.
o Select "Read Codes"
What is the code(s) present in the PCMs memory? ______
What is the generic explanation of the code(s). ______
______
o Press Exit ONCE on the scan tool. This will take you back to the previous menu.
Note: "Erasing Codes" does NOT fix the problem! You "get the code" - "fix the car" - and then "verify your repair"
F> Clearing The Code (for real - and fixing the problem)
o Reconnect the TP sensor
o Select "Clear Codes"
Clear the Codes.
Did the check engine lamp go out? ______
o Turn the vehicle OFF. Wait 10 seconds.
G> Verify Repair
o Turn on the ignition key.
o Did the MIL come on and then go out? ______
o Start the vehicle
o How does it run? ______
o Is the MIL on? ______
Note: the MIL should be off since you "fixed" the vehicle by reconnecting the TP sensor. Verifying the repair is a critical step in the repair process
Which of the following represents a typical sensor reference voltage?
A. 2 volts
B. 5 volts
C. 12 volts
D. Charging system voltage
A code that is a "hard fault"
A. Is a memory code
B. Is "bad right now"
C. Is not critical
D. All of the above
When diagnosing DTCs
A. Should be fixed in any order
B. Fix the "First code First"
C. Fix the "Last Code First"
D. All of the above
OBD II -
A. Created standardized data link connectors
B. Created standardized data link communications protocols
C. Was made federal law in 1997
D. All of the above
Once you fix the problem, do all EXCEPT
A. Go on road test
B. Make sure no new codes or repeat codes show up on the road test
C. Park the car - you don't need to test it - you're Super Tech!
D. Keep track of all past codes
The check engine lamp is on - Do all EXCEPT
A. Get the codes - write them down - Clear them - Re run self-test(s)
B. Do a visual inspection of all fuel, air, and ignition components
C. Check for loose vacuum lines, or intake leaks
D. Get codes and clear them - Park the vehicle - Its Fixed.
NATEF TASKS - VIII. ENGINE PERFORMANCE
VIII. ENGINE PERFORMANCE
B. Computerized Engine Controls Diagnosis and Repair
1. Retrieve and record stored OBD I diagnostic trouble codes; clear codes. P-3
2. Retrieve and record stored OBD II diagnostic trouble codes; clear codes when applicable. P-1
3. Diagnose the causes of emissions or driveability concerns resulting from malfunctions in the computerized engine control system with stored diagnostic trouble codes. P-1
7 Obtain and interpret scan tool data.P-1
8. Access and use service information to perform step-by-step diagnosis. P-1
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