P1682 code – Causes, information & Fix


 A P1682 error code indicates a problem in the difference between the ignition switch circuit 1 and 2. It can be caused by a lot of factors but can also be easily fixed. In this article, we are going to look at the causes of this error code as well as how to diagnose and fix it.

A P1682 error code usually means that the ignition switch or either of its circuits, or both, are damaged. The ignition switch is responsible for providing electric current to the starter so that the engine can start.

The ignition switch is sometimes part of an anti-lock theft system. Testing an ignition switch comes when you have replaced a bad ignition switch with a new one. Doing this requires that your ignition key is programmed since the antitheft system has been restructured.

What are the signs of a P1682 error code?

When the battery warning lights come on, this is usually your first sign that there may be something wrong with the ignition switch. However, this sign is not accurate as the warning light is very general and may be indicating a problem with the battery itself. There are a number of symptoms that indicate a problem with the ignition switch and they include:

Dimming headlights:

One of the most common symptoms of a bad ignition switch is dimming headlights. Sometimes if the ignition switch has serious problem, the dash board and warning lights may also be affected becoming dim as well. If you notice that the headlights grown dimmer as you accelerate and brighter when you’re slowing down, it is likely that the ignition switch has a problem. The lights may flicker instead of dimming, but both of these indicate a bad or blown indicator.

Weak or dead battery

A weak battery usually indicates a bad ignition switch. Since the ignition switch is supposed to replenish the battery, it would mean that if the battery is weak or dead, the ignition switch is bad too. Once the ignition switch goes bad, the vehicle’s electric components will draw power directly from the battery draining it faster and causing it to die quickly.

Strange noises:

The ignition switch has a lot of moving parts that work together in harmony when it is working correctly. If any of these parts break or dislocate or wear, you may hear strange sounds coming from the hood of your car. One of the noises you might hear is a grinding noise.

The grinding noise is usually caused by worn out bearings. You may also hear a whining noise. This would be a problem with the voltage regulator which is part of the ignition switch. Any of these noises should be checked immediately to prevent further damage.

Stalling engine:

The engine may stall or crank up when starting or even when driving. This is an indicator of a bad ignition switch. If the car engine fails to start or has difficulty starting, it could be because of a dying battery. Sure the problem might be independently the battery but once you’ve eliminated this possibility, then the ignition switch is the problem.

Electric failures:

We’ve already seen that the ignition switch is responsible for the powering of all the car’s electric components. It you notice that these components are failing or acting up all around the same time, this is no coincidence – it is very likely that the ignition switch has gone bad.

Blown fuse box:

Alternators have fuses that prevent electric surges from damaging the components. However, these fuses can sometimes blow due to strong surges or old age. Once they blow, the alternator cannot charge the battery. Since not all vehicles have a fuse box, you should investigate to see whether your car has one for proper diagnosis. There are symptoms that indicate a bad fuse box, they include:

Frequent blowing of fuses:

If fuses have been often blowing, this might indicate a problem with the fuse box entirely. It might mean there is a short in the fuse ox causing the fuses inside it to blow. The fuse box should be removed, disassembled and examined to find the root cause of the problem.

Loose Fuses:

If fuses fall off easily or hang loosely, this might indicate the terminals of the fuse panel are damaged. This problem will cause electrical problems in the vehicle such as intermittent power loss to accessory and warning lights.

Burnt out fuses and terminals:

This is more serious problem compared to the previous two. If the terminals or fuses are overheated for any reason they may overheat and burn up. The terminals or the plastic that makes them may burn and melt. This will require a full panel replacement and sometimes rewiring of the panels.

These are the most common symptoms of a bad or blown ignition switch. It is recommended that you fix ignition switch issues either by replacing or repairing to prevent further and serious damage.

How to test an ignition switch

The ignition switch is responsible for providing electric current to the starter so that the engine can start. The following steps show how to test your new ignition switch. For this procedure, ensure you have a voltmeter.

  1. Open the starter panel under the steering wheel and pull out the starter fuse
  2. Check the fuse for damage such as burns and if any, replace the fuse with a new one
  3. Open the hood and use the voltmeter by connecting the red terminal of the voltmeter to the positive terminal of the battery. The black end should be touched anywhere on the frame of the car. The voltmeter should read 12.6V. Anything less than 12V means the battery is dead
  4. Crank up the engine and if it cranks up, the ignition switch is fine. Otherwise, the switch is either faulty of not properly connected. If you hear a click sound, then the switch is not the problem.

How to fix P1682 error code

Depending on what the cause of the noise is, ticking noise have different fixes and prevention measures. They include:

  1. Check oil levels regularly, like once a month, using a dipstick to ensure you have enough. Check oil pressure with special gauges designed for this purpose. Recommended pressure is between 15 and 20 PSI. Also remember that oil should be checked when the engine is warm at idle.
  2. To fix valves that are worn out or out of adjustment, you need to replace the old shims with new ones and adjusting the rocker arms. If you have a pushrod engine, ensure the lifters are clean as oil deposits tend to accumulate on them over time causing the ticking noise. The silver lining to this problem is that it is the easiest and cheapest to fix.
  3. A rod knock problem can be fixed using the following steps:
  • Drain out all the oil
  • Replace the oil filter with a new one. Install and close tightly using wrench
  • Clean the fuel injector to prevent debris from getting into the engine.
  • Put in new fresh oil, about five quarts. Check the rod bearings while at it and ensure they are shut tightly
  1. Replace any worn out or damaged spark plugs
  2. For fan problems, Check for any loose bolts or shredded radiator. Tighten anything loose and replace the damaged radiator to fix this issue
  3. Replace any worn out engine components such as pistons and shafts with new ones


The ignition switch is rarely damaged. However when it does happen, it is recommended that you fix it immediately by replacing with a new one. Remember to also get the lock system reprogrammed to accommodate the new ignition switch.

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Steven Reilly
Steven Reilly is a qualified mechanic and his passion for cars goes beyond just the technical aspects. He is also an amateur racer and all round car enthusiast. When he is not driving them, he can often be found in his garage under the hood of a rare model. Steven Reilly has lost track of the number of hours he has spent setting up his fine collection of rebuilt models. He believes that cars can provide a constructive and fun opportunity to teach the youth important life skills. In line with this, he is developing a community outreach program, potentially dubbed ‘Cars for change'.


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