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Home >> Suzuki >> 2004 >> Swift + >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.6L (L91) (DTC P0502 To DTC U0426) >> Diagnostic Information & Procedures >> DTC P1392 >> Test Description
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Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  The rough road sensor will give correct voltages only if it is level and mounted securely to its bracket.
DTC P1392

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Connector End Views  or  Engine Control Module (ECM) Connector End Views 
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 
  1. Start the engine.
  2. Allow the engine to idle.
  3. Observe the rough road sensor voltage parameter with a scan tool.
Is the voltage less than the specified value?		 0.10 V Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Intermittent Conditions
4
  1. Turn OFF the ignition.
  2. Disconnect the rough road sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the Rough Road sensor to a good ground.
Is the voltage within the specified range?		 4.8-5.2 V Go to Step 5  Go to Step 7 
5
  1. Connect a 3-amp fused jumper wire between the 5-volt reference circuit and the signal circuit of the rough road sensor.
  2. Observe the Rough Road sensor voltage parameter with a scan tool.
Is the voltage more than the specified value?		 4.8 V Go to Step 6  Go to Step 8 
6 Measure the resistance between the low reference circuit of the rough road sensor and the engine control module (ECM) housing with a DMM.
Is the resistance less than the specified value?		 2 Ω Go to Step 10  Go to Step 9 
7
IMPORTANT: The 5-volt reference circuits are internally and externally connected at the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors.
Test the 5-volt reference circuit of the rough road sensor for the following conditions:
  • An open
  • A short to ground
  • High resistance
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
8 Test the signal circuit of the rough road sensor for the following conditions:
  • An open
  • A short to ground
  • High resistance

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
9
IMPORTANT: The ECM and/or the rough road sensor may be damaged if the low reference circuit is shorted to battery positive voltage.
Test the low reference circuit of the rough road sensor for the following conditions:
  • An open
  • High resistance
  • A short to voltage
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
10 Test for shorted terminals and for a poor connection at the rough road sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 12 
11 Test for shorted terminals and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
12 Replace the rough road sensor. Refer to ROUGH ROAD SENSOR REPLACEMENT .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 15 
15 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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