Diagnostic Aids

Code P1558 may set if cruise control throttle cable binds or intermittently sticks. Outside interference such as a CB antenna lead near PCM wiring harness may induce a false SPS signal and set Code P1558.

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for:

• Poor Connection Or Damaged Harness:  Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Fig 1: Code P1558 Schematic (3.8L) Cruise System Problem SPS Indicated Low

Fig 2: Code P1558 Flow Chart (3.8L) Cruise System Problem SPS Indicated Low