Watch as I create high voltage short circuits to the vehicle chassis and cause "Loss of Isolation" trouble codes to set. Learn how the vehicle detects these short circuits and how you can diagnose their source with a Megohmmeter. A 2017 Chevrolet Bolt EV is the test vehicle.
TIMELINE:
0:00 Introduction
0:25 Safety Warning
0:40 High Voltage (HV) Insulation/Isolation example
2:50 On-Car high voltage power distribution
4:55 Live HV measurements (Car Powered Off)
6:15 Live HV measurements (Car Powered On)
7:36 MUST-SEE: Shorting the 381V battery positive cable to vehicle chassis
9:57 Which Diagnostic Trouble Codes (DTC)s were set
11:18 MUST-SEE: Shorting the 381V battery negative cable to vehicle chassis
13:25 What can happen in an automobile accident
13:50 MUST-SEE: How loss of isolation can occur through conductive liquids
14:41 How the car performs active isolation testing and passive isolation testing
16:10 Normal passive scan tool data values for loss of isolation detection
18:30 See the results of an 11 Mega-ohm connection to vehicle chassis
20:50 See the results of a 4.65 Mega-ohm connection to vehicle chassis
22:20 See the results of a 1.16 Mega-ohm connection to vehicle chassis
23:00 See the results of a 551 kilo-ohm connection to vehicle chassis
23:35 See the results of a 222 kilo-ohm connection to vehicle chassis
23:40 MUST-SEE: The 318-265 kilo-ohm threshold to trigger a loss of isolation DTC
24:50 MUST-SEE: GM On-Star notification of battery problem
25:15 See the results of a 110 thousand ohm connection to vehicle chassis
25:51 MUST-SEE: See the results of a 0 (zero) ohm connection to vehicle chassis
26:54 See my voltage drop measurement table
27:35 MUST-SEE: See the results of a conductive liquid connection to vehicle chassis
30:00 How to determine the location of a loss of isolation problem
32:08 Clearing Secured High Voltage DTCs with a GM GDS2 scan tool
33:00 Hybrid/EV battery pack active isolation test
34:35 Hybrid/EV battery pack heater passive isolation test
37:28 The Megohmmeter and the factory specifications for isolation resistance
40:30 Example of using the Fluke 1587 Insulation Tester (Megohmmeter)
44:05 Video summary
ABOUT US:
Weber State University (WSU) - Department of Automotive Technology - Ardell Brown Technology Wing - Transmission Lab. This episode covers what happens with the high voltage system that loses isolation (High Voltage Leak) with the vehicle chassis of an electric vehicle (EV), plug-in electric vehicle (PHEV), or hybrid electric vehicle (HEV). A 2017 Chevrolet Bolt EV is used as an example vehicle in this video.
WSU is a leader in Hybrid and Electric Vehicle education. This topic is taught as part of our 4-year bachelor's degree program. For information on joining the Weber Automotive program, visit: http://www.weber.edu/automotive
This video was created and edited by Professor John D. Kelly at WSU. For a full biography, see http://www.weber.edu/automotive/J_Kelly.html
ADDITIONAL TRAINING FOR YOU
Join us for hybrid and electric vehicle training with two online courses and in a 5-day on-campus boot camp with Professor John D. Kelly. See http://www.weber.edu/evtraining
DONATE TO OUR DEPARTMENT
Please consider a donation to the Department of Automotive Technology at Weber State University here: http://advancement.weber.edu/Automotive