Rick's Free Auto Repair Advice

GM P1682

Diagnose and fix GM P1682:  Ignition 1 Switch Circuit 2

GM has issued a service bulletin #PIT4016F to address a GM P1682 trouble code and no crank, delayed crank, or unwanted crank condition on the vehicles listed below. The problem appears as a crank, no start, or an intermittent no start along with a check engine light and GM P1682 trouble code. You may find that you have to hold the key in the start position for several seconds until vehicle cranks and starts. In another scenario, you may turn the key to the RUN position and then back to the OFF position without cranking the vehicle and find that the starter cranks the vehicle for 5-10 seconds even though you haven’t turned the key to the full START positon.

GM service bulletin #PIT4016F recommends checking for an aftermarket accessory that may be connected to the ignition switch circuits. Shops report that circuit 4 of the ignition switch to be the most common circuit used by DIYers and aftermarket installers.

Check the ECM-IGM fuse for GMP1682 issue

Locate the ECM-IGN fuse #56 and the ECM/THROT CONT fuse# 5 and check the voltage at each when the problem occurs. The voltages should be the same. However, if the voltage on the ECM/THROT CONT fuse# 5 is less than the voltage at ECM-IGN fuse #56, the problem may be due to pitted/corroded contacts in the PWR/TRN relay. Swap that relay with a different relay of the same size and type. If that works, replace the PWR/TRN

PWR/TRN relay

Vehicles affected by service bulletin #PIT4016F

2007 – 2013 Cadillac Escalade Models
2007 – 2013 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2007 – 2013 GMC Sierra, Yukon, Yukon Denali, Yukon XL, Yukon Denali XL
2006 – 2011 Cadillac DTS
2006 – 2013 Chevrolet Impala
2006 – 2012 Buick Lucerne
2008 – 2009 Hummer H2

©, Ric Muscoplat

Posted on by Rick Muscoplat

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