Any ideas on what could be causing this code? It's a P0332, for rear knock sensor, low voltage. I got this after installing new Pfadt Headers and intake manifold seals.

Got around to removing the intake, and installed a new harness and two new Delco sensors. First startup and run was fine. Second startup and the CEL came back on; again, P0332.

It's ways the second startup the light and code comes back.

Is this actually detecting KNOCK, or is it a voltage issue? Everything is brand new. I'm stumped.

 

Couple of things.
I've seen this problem before, but it wasn't my car so I never got completely to the bottom of it. Meaning you're not on your own.
Don't some of these sensors come DOA? (Dead on arrival)
They are torque sensitive, I presume you tightened them precisely?
The only way to really see what's going on in real time is to have a scanner, example HP tuners. Have you done any logging? Is the tune stock?

 

I agree I've had a couple sensors be DOA on arrival or go bad in a few weeks. Albeit after going to delcos I never had another issue although you could have still gotten a dud. When you pull it back off ohm check the harness to make sure its all good as well as make sure they are torqued correctly. I would put the new sensor in the front and the known good one in back that way if the code dos come back you can eliminate a few issues

 

Thanks for chiming in Steve:

Yes, I torqued them both to 15ftlbs. I've got a pocket scanner, but don't know if it will do anything real time.

The tune is from Geoff @ EPS, and the code existed then when we got on the dyno. We cleared it and it didn't come back all day, after several starts and runs.

I do plan to do this Tuesday when I get home.

Stupid question... Where do I put the leads to ohm the components on the KS's?

What setting to have the multimeter on for voltage? I'd like to leave the harness plugged in and turn the cars power ON, and actually read what voltage I'm getting at the harness plug. I believe both should be 5 volts?

If I'm still getting nothing from the rear, then I'd check for power straight from the pigtail on the body harness side, to see if there's a short from the PCM to the pigtail. (After checking KS harness itself, of course)

 

Anyway, my first thought was swap front to rear and see if the code moved to the front, but that's a lot of work removing and installing KS's, and the manifold itself just to find that out.

What ohms should I be looking for from a good, as well as bad knock sensor? What's the range?

What voltage am I looking for at the KS harness with the car on?

What voltage from the body harness side pigtail?

 

Engine Off

The KS range is 93-107K ohm (good), so set you DMM to 400Kohm scale.
I also find no set voltage at all listed to check for with a P0332 in my gm service manual.
Here's another check.
Connect a DMM to the sensor side of harness and engine block. Set DMM to AC voltage.
Tap on the engine near the appropriate KS while observing for a signal indicated on the DMM. Any signal indicated on the DMM is good, otherwise the KS is bad.

Also it wouldn't hurt to check the PCM ground on the back of the heads.

 

I'd replace whichever one is throwing the code honestly. No reason is doing all that work for diagnosis.

 

Some scantools show knock counts, you can tap on head or block with a wrench and watch the scantool (or DMM set to ACV as 99Bluz28 said above).

You might also want to check the subharness-to-harness connector/pins, they might be loose/damaged/corroded.

 

do you have 02 extensions?

 

The pins I agree... I need to check them on the body pigtail side.

Negative. Repinned the PCM So the rears read as the fronts.

 

Bad gas??

 

4 tanks, either Chevron or Shell 93.

Is a 0332 an actual KNOCK code, or just saying my rear sensor isn't getting the supplied voltage it needs?

 

Did you ever get this figured out Dave? Was re-pinning the PCM pretty simple?

 

Repinning was a CAKE WALK on the Camaro. The Vette was a bit more challenging, considering I was working in the passenger wheel well, upside down.

I get home tomorrow, and there's a new AC Delco in the mail already on its way to me.

 

Anyone have any suggestions on which Harbor Freight multimeter to get? There's one for 44 bucks that's green... Looks pretty nice

 

I have seen the knock sensor get pinched in between the intake and the head before and cut the harness. Or sometimes it can get wrapped around the oil pressure sensor and get strained and pulled in 2. You cannot tell because the harness is covered with tape and that expanded nylon cover. Or sometimes the intake underneath can mash the wires and make them not work.

 

I checked all that, other than continuity between the PCM pin and the body side pigtail.

New harness, and new KS's.

Off to get a multimeter tomorrow and find out once and for all if it truly is an electrical issue or what.

 

I've got this one and it works fine:

http://www.harborfreight.com/ac-dc-d...ter-37772.html

 

We know the replacement that was sent is good...

 

Found the culprit...





Completely sliced on the body side pigtail...