When you see the P0704 code pop up, you’re dealing with what we call the “Clutch Switch Input Circuit.” Speaking from years in the shop, this means your vehicle’s PCM (that’s the powertrain control module) is monitoring the clutch pedal through a small but vital part-the clutch switch. Basically, this switch’s job is to let the computer know when your foot is pressing the clutch. That way, the engine only cranks when the pedal is fully down, keeping you from launching forward by accident. If the PCM gets a signal that doesn’t add up-or no signal at all-it throws the code and flips on your check engine light. I’ve seen this system tie into the starting circuit, and on some vehicles, it even affects cruise control or how the transmission logic behaves. It’s a simple setup, but when it goes sideways, it can really throw you for a loop.
DTC P0704
4597
6 minutes of readingCauses of P0704 code
From my time under the hood, I can tell you the clutch switch itself is usually the troublemaker behind p0704. But don’t stop there-there are a handful of other things I always check. Here’s my typical go-to list:
- Bad clutch switch (this one’s almost always to blame)
- Worn clutch pedal bushing (can knock the switch out of alignment, or cause poor contact)
- Frayed, broken, or otherwise damaged wires running to the switch
- Blown fuse in the clutch or starter circuit
- Rarely, a glitchy PCM or oddball programming issue
Nine times out of ten, it’s something basic. My advice? Rule out the simple fixes before you start chasing down unicorns or spending big on parts you don’t need.
Symptoms of P0704 engine code
If you’ve ever had this code come up, you’ll likely spot a couple red flags right away. First and foremost, that check engine light will be staring you down. But the real headache is when you go to start the car, push the clutch pedal, and nothing happens. Sometimes, you might notice cruise control acting up, or the car doing something funky when you try to fire it up. Bottom line: if you run into these symptoms, don’t brush them off. They’re your car’s way of waving a caution flag about the clutch safety circuit.
Diagnosis with dtc P0704
When I’m handed a car with dtc P0704, here’s the routine I follow-always start with the basics and work your way deeper:
- First off, I step on the clutch and feel for anything odd-looseness or wobble usually means the pedal bushing is shot.
- Next, I track down the clutch switch, usually tucked up by the clutch pedal. I check it’s snug and that the wiring’s not hanging loose or chewed up.
- With the ignition off, I’ll unplug the switch and take a close look at the connector-corrosion or bent pins are a dead giveaway. I’ll hit it with some electrical contact cleaner for good measure.
- Then, out comes the multimeter. I check for continuity through the switch while working the pedal. If it doesn’t open and close as it should, that switch is toast.
- Don’t skip the fuse for the clutch or starter circuit. If it’s blown, swap it, but remember-fuses blow for a reason, so don’t ignore the root cause.
- If everything’s still looking good, I’ll trace the wiring for any signs of damage-pinched wires under the dash are more common than you’d think.
- I only start suspecting the PCM once I’ve run out of other options-and honestly, that’s a rare day in the garage.
Pro tip: have someone work the pedal while you eyeball the switch in action. Take your time-missing a small detail here can mean a lot more work (and frustration) later.
Common Mistakes when repairing P0704
A classic mistake I see is folks swapping out the clutch switch right away, without checking the wiring or the pedal bushings. That’s money down the drain if those aren’t the real problem. Another one? Overlooking a cooked fuse or failing to notice a misaligned switch because the pedal bushing’s worn down. Always find the actual source before grabbing new parts. Skipping the basics is a fast track to wasted time and unnecessary expense-I’ve watched it happen more times than I can count.
Seriousness of obd2 code P0704
Let me put it this way: you don’t want to ignore P0704. If your car won’t start because of it, you’re one tow away from a really bad day. Even if it’s still running, a faulty clutch switch is a real safety risk-your car could jump forward if the safety’s out of whack. And if you keep cranking the engine with the issue unresolved, you could fry the starter or damage wiring. My advice? Don’t gamble with this one. Get it checked out before you’re stuck on the side of the road or facing a bigger repair bill.
Repairing obd code P0704
Most fixes for obd code P0704 are refreshingly straightforward. Here’s what I usually do to get things back on track:
- Swap out the clutch switch if it fails continuity checks
- Fix or replace any damaged wires or sketchy connectors
- Install a new clutch pedal bushing if the old one’s letting the switch misalign
- Replace any blown fuses-and always hunt down why it blew in the first place
- If you’ve ruled out everything else, only then look at the PCM for reprogramming or replacement (but that’s rare in the real world)
Your best bet? Tackle the obvious stuff-switch, wiring, fuse-before chasing after more complicated or costly fixes.
Conclusion
So here’s the bottom line: P0704 means your car’s computer isn’t hearing from the clutch pedal like it should, which can leave you stranded and light up that check engine warning. This is a critical safety feature-don’t let it slide. Check the clutch switch, poke around the wiring, inspect the pedal bushings, and don’t forget about the fuses. Usually, you’ll find a simple fix lurking in there, and taking the right approach saves time, cash, and headaches down the road. If electrical troubleshooting isn’t your thing, don’t hesitate to call in a pro-when it comes to starting and safety, it’s better to be safe than sorry.
