Question

What causes the P1682 code, and how do you fix it?

The P1682 trouble code shows up when the ECM finds a voltage difference that is higher than the allowed limit between Circuit 1 and Circuit 2. In GM vehicles, this code is defined as ‘Driver 5 Line 2.’ In non-GM models, it is defined as ‘Ignition 1 Switch Circuit 2’.

In simple terms, the P1682 code issue occurs if something is wrong with the ignition switch or the circuits that provide the ECM with battery power. 

When this code is present, the engine may crank, but the car stays in a no-start condition, and in some situations, there will be no crank at all. You may also experience a weak or dead battery, noises from the hood because of wear and tear, dimming headlights, and warning lights turning on. The check engine light gets blinking, the trouble code stays stored, and sometimes a loose fuse or a blown fuse box becomes the reason. Other codes may also show up due to the same main issue. 

What are the causes of P1682? 

The most common cause of P1682 is a defective ignition switch. The code can also appear if the ignition switch harness is open or shorted, if the electrical connections in the ignition switch circuit are damaged, or if the insulation is broken and bare wires are exposed. Faulty fuses or fuse boxes, fuel pumps that are not working correctly, and in some cases, even a defective ECM can also trigger the code. 

How to fix P1682? 

Fixing the P1682 code usually starts with replacing the ignition switch, which will most likely remove the error. If the problem still continues, start by checking the fuse box and looking for any loose wiring in connections. If not, changing the relays can also help. In the worst cases, replacing the ECM will be the only solution.