Owner's Problem Description
The owner reports that their 1977 Chevy Suburban sometimes fails to start, showing no signs of power or clicking when attempting to start. At other times, it starts normally. The starter motor has been tested and is functioning correctly. The problem occurs intermittently, particularly after driving and then trying to restart the vehicle after a short period. The owner is seeking guidance on potential causes of this issue.
Professional Technical Analysis
The 1977 Chevy Suburban, equipped with a 5.7L (350 CID) V8 engine and an estimated mileage of around 120,000 miles, exhibits an intermittent starting issue. The symptoms manifest as a complete lack of response when the ignition key is turned - no clicking or cranking sounds. This phenomenon typically occurs after the vehicle has been driven and parked briefly, leading to uncertainty in its starting reliability. Previous repair attempts have included a thorough inspection of the starter motor, which has been confirmed functional. The vehicle's electrical system is operational as evidenced by functional headlights and dashboard indicators. A critical area to investigate is the starter solenoid connections, particularly the small wire connecting to the fuse box, which is known to suffer from poor connections or corrosion on older models. These intermittent failures can often be rooted in electrical connection issues, especially in older vehicles where wire fatigue or corrosion is common due to age and exposure. The starting system relies heavily on stable voltage supply conditions, which could be compromised if the ignition switch or solenoid connections are faulty. Furthermore, potential issues within the ignition switch itself or the neutral safety switch should also be considered, as they can create intermittent faults that prevent the starter from receiving the necessary power to engage. A detailed examination of voltage at the starter solenoid and related wiring will be essential in pinpointing the root cause of this starting issue.
Possible Causes
Most common causes (ordered by frequency):
- Faulty Ignition Switch: The ignition switch may have internal wear or failure causing intermittent connectivity. This can prevent power from reaching the starter solenoid when the key is turned. Testing the switch with a multimeter for proper continuity and voltage output in the 'start' position is recommended. - Testing reveals no voltage at the starter solenoid during the 'start' position; voltage appears when the key is turned to 'on'.
- Corroded or Loose Starter Connections: The connection at the starter solenoid, particularly the small wire connecting to the fuse box, can become corroded or loose over time. This can lead to intermittent power loss to the starter. Visual inspection and tightening or cleaning the connections can help. - Visual inspection shows signs of corrosion or loose connections; intermittent operation when connections are jostled.
- Neutral Safety Switch Malfunction: If the neutral safety switch is faulty or misaligned, it may prevent the vehicle from starting unless in the proper gear (usually 'Park' or 'Neutral'). Testing the switch for continuity in different gear positions can identify this issue. - No start condition when in 'Park', but starts in 'Neutral'; switch shows inconsistent continuity.
- Starter Relay Failure: The starter relay is responsible for supplying power to the starter motor. If the relay is failing or has internal damage, it may not activate properly. Testing the relay functionality can confirm if this is the issue. - Relay fails to click or supply power when activated; testing confirms relay integrity.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Voltage Check at Starter: Use a multimeter to check for 12V at the starter solenoid when the ignition is turned to the 'start' position. If no voltage is detected, further investigate the ignition switch and wiring to the starter.
- STEP 2 - Inspect Connections: Visually inspect the starter connections, particularly the small wire going to the fuse box. Look for signs of corrosion or loose connections. Clean and secure any questionable connections found.
- STEP 3 - Test Ignition Switch: With the key in the 'start' position, test the ignition switch for voltage output at its terminals using a multimeter. Ensure continuity exists through the switch during the starting process.
- STEP 4 - Check Neutral Safety Switch: Test the neutral safety switch for continuity while shifting through 'Park' and 'Neutral'. If there's no continuity in the correct positions, replace the switch.
