77 BII map testing
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77 BII map testing
I have a code 22 on my Bronco (map out of self test range) and was wondering if there is a way to test the sensor. I read somewhere they seldom go bad-it is usually the associated wiring.
Your thoughts are appreciated.................John
Your thoughts are appreciated.................John
Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
You should run the pinpoint tests, these will help you determine the exact cause of the code. You might be able to get them at the local library, if you can't I should be able to email them to you.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
Pinpoint tests can be found in the factory manuals, or in any professional edition manual. Libraries around here either have Mitchell or Motor manuals. Sometimes they separate emissions testing into a separate manual from the chassis repair manual.
Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
DF1 CHECK FOR POWER TO MAP/ BARO SENSOR
Possible Causes:
-- Damaged MAP/BARO sensor.
-- Vacuum trapped at MAP/BARO sensor.
-- High atmospheric pressure.
-- Damaged PCM.
-- Damaged MAP/BARO circuit.
l Key off.
l Disconnect the MAP/BARO sensor from the vehicle harness.
l Connect the MAP/BP sensor tester between the vehicle harness connector and the MAP/BARO sensor.
l Insert MAP/BP sensor tester banana plugs into digital multimeter.
l Key on.
l NOTE:
Green light on tester indicates VREF is OK (4-6 volts). Red light (or no light) indicates VREF is too low or too high.
Observe tester for red or green light.
l Is green light on?
Yes
GO to «DF3».
No
GO to «DF2».
DF2 CHECK FOR POWER AT SENSOR VEHICLE HARNESS CONNECTOR
l Key on.
l MAP/BARO tester connected.
l Digital multimeter connected to MAP/BP sensor tester.
l Disconnect MAP/BARO sensor.
l NOTE:
Green light reaffirms that VREF Is OK (4-6 volts). Red light (or no light) indicates VREF is too low or too high.
Observe tester for red or green light.
l Is green light on?
Yes
REPLACE MAP/BARO sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
No
REPAIR VREF circuit. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF3 CHECK MAP/BARO SENSOR OUTPUT
NOTE:
Measure several known good MAP/BARO sensors on available vehicles. That voltage will be typical for your location on the day of testing.
l Key on.
l MAP/ BARO tester connected.
l Voltmeter connected to MAP/ BARO tester.
l Measure MAP/ BARO sensor voltage on customer vehicle.
l Is voltage in range for your altitude?
MAP/BARO EXPECTED VOLTAGE
³ Approximate Altitude Meters (Ft.) ³ Voltage Output (ñ0.04 Volt) ³
³ 0 ³ 1.59 ³
³ 305 (1000) ³ 1.56 ³
³ 610 (2000) ³ 1.53 ³
³ 915 (3000) ³ 1.50 ³
³ 1220 (4000) ³ 1.47 ³
³ 1525 (5000) ³ 1.44 ³
³ 1830 (6000) ³ 1.41 ³
³ 2135 (7000) ³ 1.39 ³
Yes
REMOVE MAP/BARO tester. GO to «DF4».
No
REMOVE MAP/BARO tester. GO to «DF5».
DF4 CHECK MAP/BARO CIRCUIT RESISTANCE
l Key off.
l MAP/BARO sensor disconnected.
l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires. Service as necessary.
l Install breakout box. Leave PCM disconnected.
l Measure resistance between MAP/ BARO circuit at the MAP/ BARO sensor vehicle harness connector and MAP/BARO at the breakout box.
l Is resistance less than 5.0 ohms?
Yes
GO to «DF5».
No
SERVICE open circuit. REMOVE breakout box RECONNECT all components. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF5 CHECK MAP/BARO CIRCUIT FOR SHORTS TO VREF, SIG RTN AND GROUND
l Key off.
l MAP/BARO sensor disconnected.
l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires. Service as necessary.
l Install breakout box. Leave PCM disconnected.
l Measure resistance between MAP/BARO and PWR GND at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
For BARO sensor:
REPLACE BARO sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
For MAP sensors:
GO to «DF8».
No
SERVICE short circuit. REMOVE breakout box RECONNECT all components. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF8 CHECK MAP SENSOR OPERATION
l Key off.
l Disconnect vacuum supply hose from MAP sensor.
l Install vacuum pump to MAP sensor. CONNECT vacuum.
l Apply 61 kPa (18 in-Hg) vacuum to MAP supply hose to MAP sensor.
l Does MAP sensor hold vacuum?
Yes
RELEASE vacuum. GO to «DF13».
No
REPLACE MAP sensor. CONNECT vacuum supply hose to MAP sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF13 CHECK THAT VACUUM-TO-MAP SENSOR DECREASES DURING DYNAMIC RESPONSE
l Key off.
l Tee a vacuum gauge in the intake manifold vacuum supply hose at the MAP sensor.
l Perform KOER Self-Test while observing vacuum.
l Did vacuum decrease by more than 34 kPa (10 in-Hg) vacuum during Dynamic Response test?
Yes
REPLACE MAP sensor. REMOVE vacuum gauge. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
No
Electronic EC system OK. REFER to Engine Group in the Service Manual for probable causes affecting engine vacuum. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
Possible Causes:
-- Damaged MAP/BARO sensor.
-- Vacuum trapped at MAP/BARO sensor.
-- High atmospheric pressure.
-- Damaged PCM.
-- Damaged MAP/BARO circuit.
l Key off.
l Disconnect the MAP/BARO sensor from the vehicle harness.
l Connect the MAP/BP sensor tester between the vehicle harness connector and the MAP/BARO sensor.
l Insert MAP/BP sensor tester banana plugs into digital multimeter.
l Key on.
l NOTE:
Green light on tester indicates VREF is OK (4-6 volts). Red light (or no light) indicates VREF is too low or too high.
Observe tester for red or green light.
l Is green light on?
Yes
GO to «DF3».
No
GO to «DF2».
DF2 CHECK FOR POWER AT SENSOR VEHICLE HARNESS CONNECTOR
l Key on.
l MAP/BARO tester connected.
l Digital multimeter connected to MAP/BP sensor tester.
l Disconnect MAP/BARO sensor.
l NOTE:
Green light reaffirms that VREF Is OK (4-6 volts). Red light (or no light) indicates VREF is too low or too high.
Observe tester for red or green light.
l Is green light on?
Yes
REPLACE MAP/BARO sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
No
REPAIR VREF circuit. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF3 CHECK MAP/BARO SENSOR OUTPUT
NOTE:
Measure several known good MAP/BARO sensors on available vehicles. That voltage will be typical for your location on the day of testing.
l Key on.
l MAP/ BARO tester connected.
l Voltmeter connected to MAP/ BARO tester.
l Measure MAP/ BARO sensor voltage on customer vehicle.
l Is voltage in range for your altitude?
MAP/BARO EXPECTED VOLTAGE
³ Approximate Altitude Meters (Ft.) ³ Voltage Output (ñ0.04 Volt) ³
³ 0 ³ 1.59 ³
³ 305 (1000) ³ 1.56 ³
³ 610 (2000) ³ 1.53 ³
³ 915 (3000) ³ 1.50 ³
³ 1220 (4000) ³ 1.47 ³
³ 1525 (5000) ³ 1.44 ³
³ 1830 (6000) ³ 1.41 ³
³ 2135 (7000) ³ 1.39 ³
Yes
REMOVE MAP/BARO tester. GO to «DF4».
No
REMOVE MAP/BARO tester. GO to «DF5».
DF4 CHECK MAP/BARO CIRCUIT RESISTANCE
l Key off.
l MAP/BARO sensor disconnected.
l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires. Service as necessary.
l Install breakout box. Leave PCM disconnected.
l Measure resistance between MAP/ BARO circuit at the MAP/ BARO sensor vehicle harness connector and MAP/BARO at the breakout box.
l Is resistance less than 5.0 ohms?
Yes
GO to «DF5».
No
SERVICE open circuit. REMOVE breakout box RECONNECT all components. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF5 CHECK MAP/BARO CIRCUIT FOR SHORTS TO VREF, SIG RTN AND GROUND
l Key off.
l MAP/BARO sensor disconnected.
l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires. Service as necessary.
l Install breakout box. Leave PCM disconnected.
l Measure resistance between MAP/BARO and PWR GND at the breakout box.
l Is each resistance greater than 10,000 ohms?
Yes
For BARO sensor:
REPLACE BARO sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
For MAP sensors:
GO to «DF8».
No
SERVICE short circuit. REMOVE breakout box RECONNECT all components. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF8 CHECK MAP SENSOR OPERATION
l Key off.
l Disconnect vacuum supply hose from MAP sensor.
l Install vacuum pump to MAP sensor. CONNECT vacuum.
l Apply 61 kPa (18 in-Hg) vacuum to MAP supply hose to MAP sensor.
l Does MAP sensor hold vacuum?
Yes
RELEASE vacuum. GO to «DF13».
No
REPLACE MAP sensor. CONNECT vacuum supply hose to MAP sensor. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
DF13 CHECK THAT VACUUM-TO-MAP SENSOR DECREASES DURING DYNAMIC RESPONSE
l Key off.
l Tee a vacuum gauge in the intake manifold vacuum supply hose at the MAP sensor.
l Perform KOER Self-Test while observing vacuum.
l Did vacuum decrease by more than 34 kPa (10 in-Hg) vacuum during Dynamic Response test?
Yes
REPLACE MAP sensor. REMOVE vacuum gauge. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
No
Electronic EC system OK. REFER to Engine Group in the Service Manual for probable causes affecting engine vacuum. RETURN to the Test Step in «Section 3», Symptom Charts, which sent you to this Pinpoint Test.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
Sig =2.55 V. Are you using the MAP/BARO tester? The MAP sensor outputs a frequency signal, which the MAP/BARO tester converts to a voltage. If you aren't using the MAP/BARO tester, that 2.55 doesn't mean anything. You can test the MAP output without the MAP tester if your DMM has a frequency counter. Mine gives me 0.16 kHz at ambient pressure (5000 ft) and 0.11 kHz at idle vacuum.
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New User
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Sorry, I thought the tester was just a breakout box. The truck is off to school right now, I will check the frequency later, in the dark again.
Thanks............John
Thanks............John
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Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
Those numbers are certainly approximately correct. Certainly not so far out of range as to be the cause of the trouble code. Let me back you up a little. Is your code 22 a KOEO code, KOER code, or memory code? Which set(s) came back as pass (11)?
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John7894
1987 - 1996 F150 & Larger F-Series Trucks
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Jan 14, 2003 04:41 PM
