So I drove this car home with a bit of a misfire, then cleaned up the throttle body plate and replaced the battery. That is when I got a crank no start issue. I got codes and it came up as p0335. So naturally I replaced the crankshaft sensor and the issue remained with the same code. I then tested the sensor by backprobing and I confirmed getting 5volts every time metal came near it. I thought it might be a bent trigger place so I replaced that. Still the same thing. I then checked timing and it was spot on.
Frustrated I took it to a shop, they thought it was a sensor too so they replaced the CPS too. Then when they realized it wasn’t they traced the signal back to the ECU and couldn’t figure out why the ECU wasn’t reading the CPS signal so they replaced the ECU and still NO START.
The only thing I can think of is that the battery terminals were pretty corroded when I put the new battery in it. The shop says they are trying to find the break in communication on the Data Bus and going through the wiring diagram. They have had my car for a month. Can anyone help?
I’m not opposed to a new mechanic, but if you have worked in a shop before you would know mechanics typically don’t jump at the chance of inheriting a complex electrical issue. I’m posting here to gain some insight to either tell the mechanic as a tip or get the vehicle back and figure it out on my own.
digging into the wiring diagram is key- and might be extensive (read expensive.)
I had this happen on a Chevy Van, and the code was Crankshaft Position Sensor, but the fault ended up being a 5Volt reference signal shorting to ground for the Oil Pressure Sensor. Both the CPS, the OPS, and something else (I forget which now,) shared the same 5V reference signal, and when it shorted to ground on one branch, it killed the signal to all the sensors. It took me about a week to trace all my wires and find the right ones (some of that week was spent looking at the wrong wiring diagram… That didn’t help a thing… )
I’ve got a hunch that your issue is much the same.
a dedicated mechanic can find this, and without just tossing parts at it.
Crank sensor was on backwards. I hate when manufacturers don’t make parts one way to put on. Still not sure why putting an actual piece of metal all over the sensor still didn’t get me any readings. Now I have to contend with a shudder in 4th gear and what seems like a bad IAC valve (cold start low idle).
Was it the electrical connection to the sensor that was backwards? Or was the crank sensor attached to whatever it attaches to with the wrong orientation? I’m guessing it’s the latter, as the automobile engineers who design the electrical connectors usually configure the two separate parts to be nearly impossible match up w/the wrong orientation. I can see how the part on the right hand side of the photo (which I presume is the working end of the sensor) could be installed w/the wrong orientation b/c of its symmetry.
Not sure why putting metal on the sensor would cause readings. What do you mean? Those sensors usually sense a magnetic field; they are not just a metal detector. The magnetic field is often sourced by a permanent magnet on something that is rotating. Some of them also require the magnet be moving.
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