Checking communication cable to engine control module (ECM)

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

Ignition off.
Immobilizer control module disconnected
Engine control module (ECM) connected.
Breakout box connected.
Connect a voltmeter between breakout box terminal #50 (#4) and ground.
Ignition on.
Check the value on the voltmeter during the first two seconds after switching the ignition on.
1. The value oscillates between 0-12 V for the first two seconds after ignition.
  Refer to Replacing control module
2. The value is stable low during the first two seconds after ignition.
  Refer to Checking for a short-circuit to ground
3. The value is stable high during the first two seconds after ignition.
  Refer to Checking for a short-circuit to supply voltage
Fig 1: Identifying Breakout Box
Courtesy of VOLVO CARS OF NORTH AMERICA.

Fig 2: Identifying Volts Display
Courtesy of VOLVO CARS OF NORTH AMERICA.

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