Voltage Drop: Multiple Symptom Disorder — 2003 Corvette
Customer drove the vehicle in. Customer states that the driver's headlight is up and the passenger side is down. It appears that the running light is on and the instrument clusters turn signal indicators are solid on. Inspect and advise on repairs. The customer has had this problem for some time and is very intermittent.
NOTE***If the vehicle is shut off the symptom usually goes away.
The data above was how the service ticket presented the vehicle to the technician.
Notes directly from the service ticket as presented by the technician:
Perform system scan, vehicle is loaded with several DTC's. Perform system checks. Visual inspection revealed a loose Batt negative cable. Perform lighting system tests and validated failures. Perform circuit checks and Isolated the issue to G102 - loose, poor ground. See video summary demonstrating 1.2v - 3.1v while moving terminator. Dissasemble and inspect. Clean and install star washers and new nut. Recheck V drop on with system loaded and found .001v = normal.
Vehicle has other issues:
- ABS/Traction control warning messages appear when the hazards are switched on.
- Brake lamp circuit code needs to be addressed.
- 3rd brake lamp is inop.
- Battery hold down is loose, wrong battery installed
Scan all vehicle systems and retrieved the following:
- B2578 FR TS Monitor Circuit Short High
- B2583 LF TS Monitor Circuit Short High
- P1539 AC Clutch Feedback Circuit High
- B2204 Driver Window Down Sw Fault
- B2206 Driver/Pass Window Up Sw Fault
- B2208 Driver/Pass Window Down Sw Fault
- B2282 Driver Clean Battery Fault
- B2284 Driver Dirty Battery Fault
- U1016 PCM Serial Data Fault
- U1064 Lost Comms with BCM
- U1255 Class 2 Serial Data Fault
- U1096 Lost Comms with DIC / IPC System
- B2283 Passenger Clean Battery Fault
- B2285 Passenger Dirty Battery Fault
- U1064 Lost Comms with BCM
The next section breaks down how we addressed the issue which I hope helps someone else who may be presented with a similar challenge.
Time to develop a strategy and see if there are any single failure points that could result in any of the symptoms exhibited and or DTC's stored.
Since the headlights were the main complaint, I decided to take a look to see how they work. SI was consulted for operation and any details about power distribution. But before I go too deep, I paused and decided to visually inspect for any clues and I found one, a faulty battery install with loose cables. Re-securing the cable connections had no effect on the headlamp operation.
Back in SI and looking a little deeper, it was noted that Splice Pack (SP100) connects at G102 and that's where we found and verified the issue by testing voltage drop between B- and one of the splice pack feed wires. This connection is located on top of the right frame rail a few inches rearward of the radiator fan shroud mounting supports.
I assembled a short video detailing this event which I hope can help someone gain some additional knowledge on the importance of measuring voltage drop.