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Randall    (Cheeko)
Randall (Cheeko), Certified Mechanic Ford Motor Co.
Category: Ford
Satisfied Customers: 2395
Experience:  18 years as a Ford tech and still going
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96 taurus: the airbag lightand it has a trouble code of p0402

Resolved Question:

I have a 96 taurus, its flassing 34 for the airbag lightand it has a trouble code of p0402. What can I do for these?
Submitted: 7 years ago.
Category: Ford
Expert:  Randall (Cheeko) replied 7 years ago.

Hi, code 34 is listed below with the pinpoint test, you will need to do some testing to find thesource of the issue, thanks

graphic

DTC B1934: DRIVER SIDE AIR BAG CIRCUIT LOW RESISTANCE OR SHORTED- LAMP FAULT CODE 34

Normal Operation

NOTE: The air bag connector, air bag diagnostic monitor harness connector and the air bag sliding contact connector have metal spring clips that act as shorting bars. These shorting bars are built into the plastic hardshell connectors. The shorting bars are designed to short Circuit 614 (GY/O) and 615 (GY/W) together when the connectors are not mated. DO NOT attempt to remove the air bag shorting bar and measure the resistance of the air bag module.

 

 

The air bag sliding contact shorting bar may be removed to measure the air bag sliding contact resistance. Likewise, the shorting bar(s) in the air bag diagnostic monitor harness connector may be removed by removing the black spacer (locking wedge) from the connector. Use extreme caution when reinstalling the shorting bars to make sure they are installed correctly.

While the ignition switch is in the RUN position, the air bag diagnostic monitor runs periodic checks on the resistance of the driver and passenger air bag circuits. Normal resistance from Pin C1-2, Circuit 614 (GY/O)(driver air bag feed) to Pin C1-3, Circuit 615 (GY/W)(driver air bag return) is between 1.4 ohms and 2.0 ohms.

  • This resistance total results from the sum of the components in the circuit: the air bag module (approximately 1 ohm) and the air bag sliding contact (0.20 ohm to 0.35 ohm per winding, 2 windings total) plus a small amount of resistance due to the wire itself, crimps, etc.
  • If the resistance across these two pins is less than 1 ohm, the air bag diagnostic monitor will interpret this as a low resistance and the air bag diagnostic monitor will store in memory DTC B1934 and flash lamp fault code 34 on the AIR BAG indicator.
  • If the low resistance is later serviced or otherwise rises into the normal range, a DTC B1934 will be stored in memory.



Possible Causes

Low resistance across Pins C1-2, Circuit 614 (GY/O) and C1-3, Circuit 615 (GY/W) can be caused by:

  • a poorly mated air bag connector, air bag diagnostic monitor harness connector, or air bag sliding contact connector may not push the shorting bars back into their fully retracted position.
  • a damaged or worn shorting bar may short Circuits 614 (GY/O) and 615 (GY/W).
  • a short in the air bag sliding contact windings or harness wires between Circuits 614 (GY/O) and 615 (GY/W).
  • a short circuit or low resistance in the driver side air bag module. Do not attempt a direct resistance measurement of the air bag module. Follow the diagnostic procedure to determine if the air bag module resistance is lower than normal.

B1934-1 CHECK FOR HARD OR INTERMITTENT DTC

  • Connect Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent to DLC located under the instrument panel.
  • Perform on-demand self test as outlined.

Was DTC B1934 retrieved?

Yes No
NOTE: This is a hard fault. The fault condition is still present. This fault may not be cleared until it is corrected and the DTC is no longer retrieved during on-demand self-test.

GO to B1934-2 .
NOTE: This is an intermittent fault. The fault condition is not present at this time.

GO to B1934-5 .

B1934-2 MEASURE RESISTANCE

  • Deactivate system.
  • Connect NGS to DLC located under the instrument panel.
  • Perform on-demand self test as outlined.

Was DTC B1934 retrieved?

Yes No
GO to B1934-3 . EXAMINE shorting bars on driver side air bag connector. REPLACE driver side air bag module if shorting bars are normal. GO to B1934-9 .

B1934-3 CHECK FOR DTC B1934

  • Disconnect air bag simulator from driver side air bag connector.
  • Disconnect air bag diagnostic monitor.
  • Set ohmmeter to highest scale (200K ohms or AUTO).
  • Remove plastic locking wedge from gray C1 harness connector at air bag diagnostic monitor.
  • Measure resistance between diagnostic monitor harness connector Pins C1-2, Circuit 614 (GY/O) and C1-3, Circuit 615 (GY/W) while turning steering wheel.

Is the resistance reading 1 MEG ohm or more?

Yes No
REPLACE air bag diagnostic monitor if shorting bars are normal. RECONNECT system. VERIFY system. GO to B1934-9 . GO to B1934-4 .

B1934-4 CHECK FOR HARNESS SHORT

  • Disconnect air bag sliding contact at base of steering column.
  • Measure resistance between air bag diagnostic monitor harness connector Pin C1-2, Circuit 614 (GY/O) and C1-3, Circuit 615 (GY/W).

Is the resistance reading 1 MEG ohm or more?

Yes No
EXAMINE shorting bars for proper installation. REPLACE air bag sliding contact if shorting bars are normal. RECONNECT system. GO to B1934-9 . SERVICE short between Circuit 614 (GY/O) and Circuit 615 (GY/W). RECONNECT system. VERIFY system. REACTIVATE system. GO to B1934-9 .

B1934-5 CHECK FOR SERVICED DTCS

  • Deactivate system.

Has a DTC B1934 just been serviced and repaired?

Yes No
GO to B1934-9 . GO to B1934-6 .

B1934-6 CHECK SHORTING BARS

  • Disconnect air bag diagnostic monitor.
  • Set ohmmeter to lowest scale (200 ohms or AUTO).
  • Zero ohmmeter by touching leads together and record resistance reading.
  • Remove plastic locking wedge from gray harness side connector. NOTE: Intermittent shorting bar malfunction may lead to a DTC B1934.

     

     

  • Measure resistance between diagnostic monitor harness connector Pins C1-2, Circuit 614 (GY/O) and C1-3, Circuit 615 (GY/W) while wiggling wires at driver side air bag connector where it mates to air bag sliding contact. Subtract the reading found when zeroing the ohmmeter.
  • Visually inspect shorting bars in driver side air bag module, air bag sliding contact connector at main wiring harness and air bag diagnostic monitor. Look for signs of poor operation of these shorting bars.

Are any concerns noticed in the wiring or is ohmmeter reading less than 1 ohm?

Yes No
SERVICE any concerns if found. GO to B1934-9 . GO to B1934-7 .

B1934-7 CHECK AIR BAG SLIDING CONTACT

  • Remove air bag simulator from steering wheel.
  • Measure resistance between diagnostic monitor harness connector Pins C1-2, Circuit 614 (GY/O) and C1-3, Circuit 615 (GY/W) while turning steering wheel.

Is the resistance reading infinite (open)?

Yes No
REPLACE air bag sliding contact if the resistance reading jumps while turning the wheel. GO to B1934-9 . GO to B1934-8 .

B1934-8 CHECK CIRCUITS 614 (GY/O) AND 615 (GY/W)

  • Visually inspect the wiring and connections in Circuits 614 (GY/O) and 615 (GY/W). Look for potential intermittent shorts between these circuits.
  • Similarly examine air bag sliding contacts wires were air bag sliding contact mates to main harness.
  • Similarly examine air bag sliding contacts and driver side air bag module wires where air bag sliding contact mates to the driver side air bag module.

Are concerns noticed?

Yes No
SERVICE any wiring concerns found. REPLACE air bag sliding contact or driver side air bag module if air bag sliding contact wires are damaged. GO to B1934-9 . RE-EXAMINE fault code description and schematic. LOOK for causes of intermittent shorts between the appropriate circuits. ATTEMPT to recreate hard faults by driving vehicle, flexing wire harnesses, etc., cycling ignition switch frequently. SERVICE any intermittent problems if found. GO to B1934-9 .

B1934-9 CHECK FOR OTHER DTCS

    NOTE: Do not clear any DTCs until all DTCs are addressed.

     

     

  • Connect NGS to DLC located under the instrument panel.
  • Select: IABM
  • Select: Diagnostic Test Modes
  • Select: Retrieve/Clear continuous DTCs
Were any other DTCs retrieved?
Yes No
NOTE: Do not clear any DTCs until all DTCs are addressed.

 

 

REFER to DTC Index and PROCEED to proper pinpoint test to CONTINUE diagnostics.
REACTIVATE system as outlined. CLEAR all DTCs as outlined.

 

 

CODE p0402

TSB
04-11-1
  • DRIVEABILITY - STREAMLINED DIAGNOSTIC PROCEDURE FOR VEHICLES WITH MIL ON AND DTCS P0401, P0402, P1400 OR P1401 - ADDITIONAL SYMPTOMS MAY INCLUDE RUNS ROUGH, LACKS POWER, SURGE, POOR FUEL ECONOMY
Publication Date: May 25, 2004

ISSUE:

Some vehicles may exhibit a malfunction indicator lamp (MIL) "ON" with or without the following symptoms: Rough Running, Lack of Power, Surge or Poor Fuel Economy, along with diagnostic trouble codes (DTC's) P0401, P0402, P1400 or P1401. This may be caused by an intermittently functioning tube-mounted delta pressure feedback EGR (DPFE) sensor (Figure 1

graphic

Randall (Cheeko), Certified Mechanic Ford Motor Co.
Category: Ford
Satisfied Customers: 2395
Experience: 18 years as a Ford tech and still going
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