XB170 - Code 587: Check Wiring Harness

Diagnostic Trouble Code (DTC) 587 indicates a Data Communications Link (DCL) error between the Powertrain Control Module (PCM) and Variable Control Relay Module (VCRM) (DCL includes the DATA (+) and DATA (-) circuits).

Possible causes:

- Open or short in DATA (+) or DATA (-) circuit.

- Damaged VCRM.

- Damaged PCM.

- Check vehicle harness that contains the DATA (+) and DATA (-) circuits for close proximity to high voltage wires, aftermarket modifications, etc.

- Are the above checks OK?

Yes -- If Key On, Engine Off DTC 587 is present: Go to XB171. XB171 - Check Data (+) And Data (-) Circuit Continuity

For Continuous Memory DTC 587 only: Go to XB180. XB180 - Check Data (+)/Data (-) Circuits: Intermittent Concerns

No -- Service as necessary. Clear continuous memory. Clearing Diagnostic Trouble Codes

Start engine. Turn A/C "ON", wait 15 seconds. A/C "OFF". Engine "OFF". Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)