The clutch pedal or the accelerator pedal switches are maladjusted.

Adjust the switches.

Refer to Accelerator Pedal Switch and Clutch Pedal Switch.

The switches are improperly wired.

A short is present in the wiring harness.

Repair the wiring.

The exhaust manifold valve is stuck partially closed.

Loosen and lubricate the exhaust manifold valve or replace the exhaust manifold valve.

The exhaust manifold valve is adjusted so that it is partially closed.

Adjust the exhaust manifold valve.

A fuse is blown.

Replace the fuse.

The accelerator pedal or the clutch pedal switches are improperly adjusted or faulty.

Adjust or replace the clutch pedal switch or the accelerator pedal switch.

Refer to Clutch Pedal Switch or Accelerator Pedal Switch.

The following conditions exist at the switches or the control valves:

Clean or replace the switches or the control valves.

Refer to Control Valves.

The air lines exhibit any of the following conditions:

Repair the lines.

In freezing weather, ensure that the air tanks are drained.

The relay crank is seized.

Repair the relay crank.

The relay rod is broken or missing.

Repair or replace the relay rod.

The air cylinder or the control valve is jammed with ice.

Melt the ice.

In freezing weather, ensure that the air tanks are drained.

The control valve is faulty.

(The valve should open when 12 volts is applied.)

Replace the control valve.

Refer to Control Valve.

The air cylinder is faulty.

Replace the air cylinder.

A broken wire is present in the harness.

Repair the wire.

The exhaust manifold valve or the relay crank is tight.

1. Loosen the exhaust manifold valve or the relay crank.
2. Lubricate the exhaust manifold valve or the relay crank.

The accelerator pedal or clutch pedal switches are improperly adjusted.

Adjust the accelerator pedal switch or the clutch pedal switch.

The exhaust manifold valve is improperly adjusted or tight.

1. Loosen and/or adjust the exhaust manifold valve.
2. Lubricate the exhaust manifold valve, as necessary.

The relay crank is tight.

1. Loosen the relay crank.
2. Lubricate the relay crank.

The air lines are kinked or partially plugged with ice.

Repair the air lines.

In freezing weather, ensure that the air tanks are drained.

The fittings at the air lines leak.

Tighten the fittings.

Leaking air cylinder

Replace the air cylinder.

The relay crank or exhaust manifold valve is seized.

1. Loosen the relay crank or the exhaust manifold valve.
2. Lubricate the relay crank or the exhaust manifold valve.

The control valve or the air cylinder is jammed with ice.

1. Melt the ice.
2. Drain the lines.

In freezing weather, ensure that the air tanks are drained.

A short is present in the wiring harness.

(The wiring harness has 12 volts at the control solenoid in every control switch position.)

Repair the wiring.

The control switch is faulty.

Replace the control switch.