background image

EGR Valve Position

• Remove vacuum hose from EGR valve.

• Connect hand vacuum pump to EGR

valve.

• Gradually apply vacuum to slowly open

valve. (Typically, 5 to 10 in. of vacuum
fully opens valve.)

• Depending on hook-up, the display read-

ing will either increase or decrease in
resistance.

• The display reading should either start

at or end at the approximate resistance
value measured in Step 6.

9. Test Results.

Good Sensor:

Display reading gradually

increases  or  decreases in resistance as
sensor is opened and closed.

Bad Sensor:

  There is no change in resis-

tance as sensor is opened or closed.

32

Test Procedure (see Fig. 33):

1. Insert BLACK test lead into COM test

lead jack.

2. Insert RED test lead into..

 test lead jack for DC type or

low frequency type MAP sensors.

Manifold Absolute Pressure
(MAP) and Barometric
Pressure (BARO) Sensors

This sensor sends a signal to the computer
indicating atmospheric pressure and/or en-
gine vacuum. Depending on the type of MAP
sensor, the signal may be a dc voltage or a
frequency. GM, Chrysler, Honda and Toyota
use a dc voltage MAP sensor, while Ford
uses a frequency type. For other manufactur-
ers refer to vehicle service manual for type of
MAP sensor used.

Fig. 33

Ground

Red

Black

Typical

GM

MAP

Sensor

To

Computer

250V MAX

15A MAX

FUSED

COM

DC

15A

OFF

200

20

2

DC V

200

  m

20M

200
    K

20K

2K

200

8CYL

6CYL

TACH

X10

5CYL

4CYL

8CYL

6CYL

5CYL

4CYL

DWELL

DUTY
CYCLE

     %

OHMS

°

15

A

C

B

A

30

25

20

15

5

0

10

V A C U U M   P U M P

DC

Only

Frequency

Only

Summary of Contents for SunPro CP7678

Page 1: ...ttery Current Draw 16 Cranking Voltage Battery Load Test 17 Voltage Drops 18 Charging System Voltage Test 19 Ignition System Testing 20 Ignition Coil Testing 20 Ignition System Wires 22 Hall Effect Sensors Switches 23 Magnetic Pick Up Coils 24 Reluctance Sensors 24 Ignition Coil Switching Action 25 Fuel System Testing 26 Testing GM C 3 Mixture Control Solenoid Dwell 26 Measuring Fuel Injector Resi...

Page 2: ...age when the engine is running Always turn ignition key OFF when connecting or disconnecting electrical components unless otherwise instructed Always follow vehicle manufacturer s warnings cautions and service procedures CAUTION Some vehicles are equipped with safety air bags You must follow vehicle service manual cautions when working around the air bag components or wiring If the cautions are no...

Page 3: ...et reconnected in the wrong place or not at all Don t take shortcuts Inspect hoses and wiring which may be difficult to see due to location Inspect the air cleaner and ductwork for defects Check sensors and actuators for damage Inspect ignition wires for Damaged terminals Split or cracked spark plug boots Splits cuts or breaks in the ignition wires and insulation Inspect all vacuum hoses for Corre...

Page 4: ...r clips instead of test prods For these tests push the crimp end of the alligator clip onto the test prod If the crimp on the alligator clip becomes loose then remove the alligator clip from the test prod and re crimp using a pair of pliers Section 1 Multimeter Basic Functions Digital multimeters or DMMs have many special features and functions This section defines these features and functions and...

Page 5: ... and other ON OFF types of devices 11 DISPLAY Used to display all measurements and multimeter information Low Battery If this symbol appears in the lower left corner of the display then replace the internal 9V battery See Fuse and Battery replacement on page 7 Overrange Indication If 1 or 1 appears on the left side of the display then the multim eter is set to a range that is too small for the pre...

Page 6: ...ange See Fig 2 The multimeter display now shows a 1 and nothing else This means the multimeter is being overranged or in other words the value being measured is larger than the current range The range should be increased until a value is shown on the display If you are in the highest range and the multimeter is still show ing that it is overranging then the value being measured is too large for th...

Page 7: ...et the multimeter to the 2KΩ range See Fig 6 The dis play will indicate an overrange condition because 3 87KΩ is larger than 2KΩ This example shows that by decreasing the range you in crease the accuracy of your measure ment When you change the range you change the loca tion of the decimal point This changes the accuracy of the Fig 6 measurement by either increasing or decreas ing the number of di...

Page 8: ...rs are common uses for the OHMS Ω function Fig 7 To measure DC Voltages see Fig 7 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack 3 Connect RED test lead to positive side of voltage source 4 Connect BLACK test lead to negative side of voltage source NOTE If you don t know which side is positive and which side is negative then arbitrarily connect the RED ...

Page 9: ... DC Current This multimeter can be used to measure DC current in the range from 0 to 15A If the current you are measuring exceeds 15A the internal fuse will blow see Fuse Replace ment on page 7 Unlike voltage and resis tance measurements where the multimeter is connected across the component you are Fig 9 testing current measurements must be made with the multimeter in series with the compo nent I...

Page 10: ...y found in alternators on automobiles Performing Diode Test see Fig 11 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack 3 Turn multimeter rotary switch to 2K diode function No beeper on diode test 4 Touch RED and BLACK test leads to gether to test continuity Check display should reset to 0 00 5 Disconnect one end of diode from cir cuit Diode must be total...

Page 11: ...ine is cranking or running 7 View reading on display If using LO TACH display reading is actual RPM Remember to multiply display reading by 10 to get actual RPM If display reads 200 then actual engine RPM is 10 times 200 or 2000 RPM 7 Switch RED and BLACK test leads and repeat Step 6 8 Test Results If the display showed A voltage drop of 0 volts in both direc tions with the continuity beeper sound...

Page 12: ...king solenoids relays switches fuel injectors and any other compo nent that is switched ON and OFF To measure Dwell see Fig 13 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack 3 Connect RED test lead to DWELL signal wire If measuring DWELL on breaker point ignition systems connect RED test lead to negative side of primary ignition coil refer to vehicle se...

Page 13: ...n and needs to be replaced NOTE Always replace blown fuses with same type and rating Testing Switches This test checks to see if a switch Opens and Closes properly Fig 16 Red Black Typical Push Button Switch To test Switches see Fig 16 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack 3 Turn multimeter rotary switch to 200 function 4 Touch RED and BLACK te...

Page 14: ...oil Display in Step 7 is not within manufac turers specifications Display reads overrange on every ohms range indicating an open circuit NOTE Some relays and solenoids have a diode placed across the coil To test this diode see Testing Diodes on page 10 To test Solenoids and Relays see Fig 17 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack 3 Turn multimet...

Page 15: ...Battery Test Before you do any starting charging system checks you must first test the battery to make sure it is fully charged Fig 18 Black Red Test Procedure see Fig 18 1 Turn Ignition Key OFF 2 Turn ON headlights for 10 seconds to dissipate battery surface charge 3 Insert BLACK test lead into COM test lead jack 4 Insert RED test lead into test lead jack 5 Disconnect positive battery cable 6 Con...

Page 16: ... test lead to positive battery cable NOTE Do not start vehicle during this test because multimeter damage may result 7 Turn multimeter rotary switch to 15A DC position 8 View reading on display Typical current draw is 100mA 1mA 0 001A Refer to vehicle service manual for manu facturers specific Engine Off Battery Cur rent Draw NOTE Radio station presets and clocks are accounted for in the 100mA typ...

Page 17: ...cedure see Fig 20 1 Disable ignition system so vehicle won t start Disconnect the primary of the ignition coil or the distributor pick up coil or the cam crank sensor to disable the ignition sys tem Refer to vehicle service manual for disabling procedure 2 Insert BLACK test lead into COM test lead jack 3 Insert RED test lead into test lead jack 4 Connect RED test lead to positive terminal of batte...

Page 18: ...ions With this test you can find excessive resistance in the starter system This resis tancerestrictstheamountofcurrentthatreaches the starter motor resulting in low battery load voltage and a slow cranking engine at starting Test Procedure see Fig 21 1 Disable ignition system so vehicle won t start Disconnect the primary of the ignition coil or the distributor pick up coil or the cam crank sensor...

Page 19: ...f display reads 13 2 to 15 2 volts If display voltage is not between 13 2 to 15 2 volts then proceed to Step 13 8 Open throttle and Hold engine speed RPM between 1800 and 2800 RPM Hold this speed through Step 11 Have an assistance help hold speed 9 View reading on display Voltage reading should not change from Step 7 by more than 0 5V 10 Load the electrical system by turning on the lights windshie...

Page 20: ...nals are easily ac cessible Test Procedure 1 If engine is HOT let it COOL down be fore proceeding 2 Disconnect ignition coil from ignition system 6 Connect test leads Connect RED test lead to primary igni tion coil positive terminal Connect BLACK test lead to primary ig nition coil negative terminal Refer to vehicle service manual for loca tion of primary ignition coil terminals 7 View reading on ...

Page 21: ...l resistance range of secondary ignition coils is 6 0 30 0KΩ Refer to vehicle service manual for your vehicles resistance range 15 Repeat test procedure for a HOT igni tion coil NOTE It is a good idea to test ignition coils when they are both hot and cold because the resistance of the coil could change with temperature This will also help in diagnosing intermittent ignition sys tem problems 16 Tes...

Page 22: ...r means of re moval are attempted Refer to vehicle ser vice manual for procedure NOTE Some spark plug wires have sheet metal jackets with the following sym bol This type of plug wire con tains an air gap resistor and can only be checked with an oscilloscope 2 Insert BLACK test lead into COM test lead jack see Fig 25 3 Insert RED test lead into test lead jack 4 Connect RED test lead to one end of i...

Page 23: ...ors not illustrated refer to ve hicle service manual for pin locations 3 Insert BLACK test lead into COM test lead jack 4 Insert RED test lead into test lead jack 5 Connect RED test lead to sensor SIG NAL pin 6 Connect BLACK test lead to 9V battery negative pin 7 Turn multimeter rotary switch to 200 function Multimeter should sound a tone 8 Slide a flat blade of iron or magnetic steel between sens...

Page 24: ...7 Reluctance Sensor Red Black Test Procedure see Fig 27 1 Insert BLACK test lead into COM test lead jack 2 Insert RED test lead into test lead jack Reluctor Ring Magnet 3 Connect RED test lead to either sensor pin 4 Connect BLACK test lead to remaining sensor pin 5 Turn multimeter rotary switch to 2KΩ range 6 View reading on display while flexing sensor wires in several places Typical resistance r...

Page 25: ...g from the DIS module to the vehicle engine computer refer to vehicle service manual for loca tion of this wire For all vehicles with distributors connect RED test lead to negative side of primary ignition coil refer to vehicle service manual for location of ignition coil 4 Connect BLACK test lead to a good vehicle ground 5 Turn multimeter rotary switch to cor rect CYLINDER selection in LO TACH 6 ...

Page 26: ...maintain an air fuel ratio of 14 7 to 1 in order to reduce emissions This test checks to see if the solenoid dwell is varying Test Description This test is rather long and detailed Refer to vehicle service manual for the complete test procedure Some important test procedure highlights you need to pay close attention to are listed below 1 Make sure engine is at operating tem perature and running du...

Page 27: ...Refer to vehicle service manual for procedure 5 Connect RED and BLACK test leads across fuel injector pins Make sure you connect test leads across fuel injector and not the wiring harness 6 Turn multimeter rotary switch to de sired OHM range If the approximate resistance is unknown start at the largest OHM range and de crease to the appropriate range as re quired see Setting the Range on page 6 7 ...

Page 28: ... exhaust stream A low voltage high resis tance indicates a lean exhaust too much oxygen while a high voltage low resistance indicates a rich exhaust not enough oxygen The computer uses this voltage to adjust the air fuel ratio The two types of O2 Sensors commonly in use are Zirconia and Titania Refer to illustration for appearance differ ences of the two sensor types Test Procedure see Fig 30 1 If...

Page 29: ...urround sensor tip with flame to deplete sensor of oxygen Rich Condition Multimeter display should read 0 6V or greater for Zirconia Type Sen sors an Ohmic Resistance value for Titania Type Sensors Reading will vary with flame temperature While still applying heat to sensor move flame such that oxygen can reach sensor tip Lean Condition Multimeter display should read 0 4V or less for Zirconia Type...

Page 30: ...the approximate resistance is unknown start at the largest OHM range and de crease to the appropriate range as re quired See Setting the Range on page 6 9 View and record reading on display 10 Disconnect multimeter test leads from sensor and reconnect sensor wiring This step does not apply to intake air temperature sensors For intake air tem perature sensors leave multimeter test leads still conne...

Page 31: ...lead into test lead jack 3 Disconnect wiring harness from sen sor 4 Connect Test Leads Connect RED test lead to sensor POWER pin Connect BLACK test lead to sensor GROUND pin Refer to vehicle service manual for loca tion of sensor POWER and GROUND pins 5 Turn multimeter rotary switch to 20KΩ range 6 View and record reading on display Display should read some resistance value If multimeter is overra...

Page 32: ...t lead into COM test lead jack 2 Insert RED test lead into test lead jack for DC type or low frequency type MAP sensors Manifold Absolute Pressure MAP and Barometric Pressure BARO Sensors This sensor sends a signal to the computer indicating atmospheric pressure and or en gine vacuum Depending on the type of MAP sensor the signal may be a dc voltage or a frequency GM Chrysler Honda and Toyota use ...

Page 33: ...her frequency type MAP sensors refer to vehicle service manual for MAP sensor specifications It is O K if last two display digits change slightly while vacuum is held constant Remember to multiply display reading by 10 to get actual RPM To convert RPM to Frequency or vice versa use equation below Frequency RPM 30 Equation Only Valid for Multimeter in 4 Cylinder HI LO TACH Position 13 Operate Senso...

Page 34: ...o MAF signal wire Refer to vehicle service manual for loca tion of MAF signal wire You may have to backprobe or pierce MAF signal wire in order to make con nection Refer to vehicle service manual for best way to connect to MAF signal wire 5 Turn Ignition Key ON but do not start engine 6 Turn multimeter rotary switch to 20V range for DC type MAF sensors 4 Cylinder TACH position for Low Fre quency t...

Page 35: ...ervice manual for charts relating MAF sensor voltage or frequency RPM to increasing air flow Use equation above for Frequency and RPM conversions 9 Test Results Good Sensor Sensor output voltage or frequency RPM are within manufacturers specifi cations at Key ON Engine OFF Sensor output voltage or frequency RPM increase with increasing air flow Bad Sensor Sensor output voltage or frequency RPM are...

Page 36: ...e Factory Actron requests that a copy of the original dated sales receipt be returned with the unit to determine if the warranty period is still in effect This warranty does not apply to damages caused by accident alterations or improper or unreasonable use Expendable items such as batteries fuses lamp bulbs flash tubes also are excluded from the scope of this warranty ACTRON MANUFACTURING COMPANY...

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