INTRODUCTION
Pin voltage (valve) charts are used for diagnosing intermittent symptoms and faults that are unable to be resolved during self-diagnostics. Pin voltage tests ensure Powertrain Control Module (PCM) is receiving and transmitting proper voltage and other signals. Before performing pin voltage tests, ensure engine mechanical condition has been thoroughly inspected and self-diagnostics has been attempted. Technical Service Bulletins (TSBs) may also be helpful in correcting a hard to diagnose problem.
PIN VOLTAGE TESTS
| CAUTION | When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery. |
| CAUTION | Before disconnecting battery, obtain anti-theft code for radio. After battery is reconnected, CODE will appear on radio display. Enter 5-digit anti-theft code using select buttons and radio will begin working. If code is entered wrong 3 times, leave radio on at least one hour and enter code correctly. Any time radio power is lost, pre-selected radio stations will have to be set. For more information, see owners manual. |
Note. Unless stated otherwise in testing procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance. Carefully backprobe PCM harness connector using Backprobe Set (07SAZ-001000A ) to avoid connector damage. Voltage readings may vary slightly due to battery condition or charging rate.
Note. PCM may also be referred to as ECM. Generator may also be referred to an alternator.
Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at the PCM connector determines whether PCM is receiving and transmitting proper voltage signals. Diagnostic charts may also help determine if PCM harness is shorted or open. (Scheme 1)- (Scheme 3).
Scheme 1
Scheme 2
Scheme 3
See also:
• COMPUTER RELEARN PROCEDURES