Code
P1662
HUMMER
P — Powertrain
Cruise Lamp Control Circuit
AI status
Completed
Completed
100%
Causes
- Open, short, or high resistance in lamp wiring or connectors
- Failed instrument cluster lamp (bulb or LED) or socket
- Blown fuse protecting the cruise lamp circuit
- Poor or corroded ground connection
- Faulty Body Control Module (BCM) or instrument cluster driver
- Intermittent connection from damaged harness or pin backout
Symptoms
- Cruise control indicator lamp does not illuminate when cruise is enabled
- Cruise lamp may be stuck ON or flicker intermittently
- Cruise control may not engage or behave erratically
- Related body electrical warnings or other lamp circuit faults
- DTC P1662 stored in vehicle control module memory
What to check
- Read and record freeze frame and related stored codes with a scan tool
- Inspect fuses related to instrument cluster/BCM and replace if blown
- Visual inspection of instrument cluster lens, bulb/LED and socket
- Inspect wiring harness and connectors for damage, corrosion, pin push-out
- Backprobe lamp connector and measure voltage and ground while commanding lamp ON
- Check ground continuity from cluster ground to chassis with meter
Signal parameters
- Lamp supply when commanded ON: ~10–14.5 V (battery voltage with ignition ON)
- Lamp supply when OFF: ~0 V (or open circuit) for switched ground designs or battery voltage with series driver, depending on vehicle
- Ground continuity: near 0 ohms to chassis ground (
- Typical lamp current: varies by lamp type (incandescent bulbs 100–500 mA; LED indicators much lower, often tens of mA)
- Driver output may be a low-side switch (pulled to ground) or high-side; confirm with wiring diagram
Diagnostic algorithm
- Connect a capable scan tool, retrieve P1662 and any related codes, note freeze frame data.
- Visually inspect fuse(s) for instrument cluster/BCM lamp circuits; replace if blown and retest.
- Inspect instrument cluster face and lamp assembly; if removable, verify bulb/LED seating or replace lamp with a known-good unit.
- With ignition ON, command cruise lamp ON via scan tool (if available) or reproduce by enabling cruise; backprobe the lamp connector and measure voltage to verify presence of supply/driver signal and ground.
- If no voltage/ground is present, trace wiring to BCM/cluster: check connector pin voltage at the module, check for open/short to ground or battery using wiring diagram.
- Check grounds: disconnect connector and measure continuity from lamp ground pin to chassis ground; repair any high-resistance ground.
- Wiggle test harness and connectors while observing lamp operation and scan tool data to identify intermittent faults.
- If wiring and lamp are good but no driver signal, test the BCM/instrument cluster output driver per service manual (voltage injection or module bench test recommended).
- Repair or replace damaged wiring, connectors, lamp, or module as determined. After repair, clear codes and verify repair by cycling ignition and commanding lamp; confirm no return of P1662.
Likely causes
- Blown fuse or faulty lamp (bulb/LED) / socket
- Open or corroded ground at instrument cluster
- Connector/terminal corrosion or loose pin at BCM or cluster
- Wiring short to voltage or ground in harness to cluster
- Defective BCM or instrument cluster output transistor
Fault status
Status
Cruise control indicator lamp circuit fault detected — check lamp, wiring, ground, fuse, and controlling module.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
-
HUMMER: 2009
-
HUMMER: 2008
-
HUMMER: 2007
-
HUMMER: 2005
-
HUMMER: 2004
-
HUMMER: 2000
-
HUMMER: 1999
-
HUMMER: 1994
-
HUMMER: 1993
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email