P0327-Knock Sensor Circuit Low Voltage

**1slowbusa** · 03-23-2013, 11:29 AM

So i replaced the knock sensors and the harness and the wire from the PCM to the harness, even put new pins in the PCM connector that I got from the GM dealer. Oh and by the way, i replaced the PCM as well.

I am still getting P0327 knock sensor circuit low voltage. I followed the instructions in the following site. GearChatter.com :: View topic - DTC P0327 Knock Sensor (KS) 1 Circuit

I am out of ideas.

Does anyone know what the voltage is supose to be????? What is the minimum/maximum voltage.

Thanks

**1slowbusa** · 03-23-2013, 12:39 PM

I read that the code will active when the voltage is below .500v. I disconnected the pigtail harness and read both the sensors. While reving the engine, the i seen the voltage go up to around .400v. Is this right?

I just looked at the knock sensors. The original part number on the Knock sensor is 10456603.

The new knock sensors I have installed are 12589867.

**383ls6** · 03-23-2013, 02:40 PM

1. Inspect the terminals at the Knock Sensor (KS) jumper harness connector located on the left side of the intake manifold for a connection problem.

2. Check the resistance of the KS from the Dark Blue wire, pin A to ground.The front sensor is the Dark Blue wire and the rear is the Light Blue wire Should be 93-107K ohms.

3. If OK reconnect the connector.

4. Disconnect the Red connector at the Powertrain Control Module (PCM) and recheck resistance from the Dark Blue wire, pin 51.
I have installed new delco knock sensors and gotten a bad one out of the box. also dont overtorque them.

**1slowbusa** · 03-23-2013, 03:24 PM

Originally Posted by 383ls6

1. Inspect the terminals at the Knock Sensor (KS) jumper harness connector located on the left side of the intake manifold for a connection problem.

2. Check the resistance of the KS from the Dark Blue wire, pin A to ground.The front sensor is the Dark Blue wire and the rear is the Light Blue wire Should be 93-107K ohms.

3. If OK reconnect the connector.

4. Disconnect the Red connector at the Powertrain Control Module (PCM) and recheck resistance from the Dark Blue wire, pin 51.
I have installed new delco knock sensors and gotten a bad one out of the box. also dont overtorque them.

383ls6, i have done the exact troubleshooting procedure you just wrote 100 times in a row. According to the readings, everything is good.

**1slowbusa** · 03-23-2013, 03:40 PM

These are the readings I am getting. Can someone give me some readings off your car so I can do a compare since I cannot find any min/max numbers.
They go in the order of

Bank 1 resistance
Attachment 25052

Bank 1 mv at Idle
Attachment 25053

Bank 1 mv at 2000 rpm
Attachment 25054

Bank 2 resistance
Attachment 25055

Bank 2 mv at idle
Attachment 25056

Bank 2 mv at 2000 rpm
Attachment 25057

**383ls6** · 03-23-2013, 05:02 PM

wow thought i might be able to help you but those readings look perfect.as soon as you clear the code it comes right back? i know its a pain but you might try pulling the intake again and swap the sensors front to back and see if you get a p0332 now then you would now its a sensor problem or something else. if you still get the p0327 then you would know its not a sensor but plug or wiring. even though its reading right could still be a sensor. thats where i would start. torque is 15 lb/ft

**Spikito** · 03-23-2013, 05:14 PM

Ive had this problem and was told it will happen if you dont use the proper brand knock sensors, i think theyre supposed to be AC Delco. It can also happen if the harness get pinched when you install the intake manifold

**pajeff02** · 03-23-2013, 05:31 PM

I have also heard of members having issues with non-AC Delco sensors. OP -- what brand sensors did you use?

**1slowbusa** · 03-23-2013, 05:36 PM

I have replaced the sensors twice. I have purchased them straight from 2 different dealership. AC delco 12589867. which replaces the old 10456603.

**1slowbusa** · 03-23-2013, 05:44 PM

Originally Posted by 383ls6

wow thought i might be able to help you but those readings look perfect.as soon as you clear the code it comes right back? i know its a pain but you might try pulling the intake again and swap the sensors front to back and see if you get a p0332 now then you would now its a sensor problem or something else. if you still get the p0327 then you would know its not a sensor but plug or wiring. even though its reading right could still be a sensor. thats where i would start. torque is 15 lb/ft

The code comes back after a couple miles of driving but sometimes it comes back after roughly 10 miles of driving. I always torque the sensors to 15 lb/ft.

The car is not stock, the modifications are g5x3, ARP head studs, AFR 205 heads, cometic .040 head gaskets, comp cam 921 springs, 7.4 push rods, yella terra lifters, rollmaster double roller, ls6 ported oil pump, 1/7/8 tsp headers, tsp catted ypipe.
Right now i have a ls6 intake with stock throttle body on the car but i had a fast 102 with a nick william throttle body but took it off because i thought it might be causing some sort of issues. But that wasnt it.

Hope this helps, i am out of ideas.

**383ls6** · 03-24-2013, 08:52 AM

do you have access to a scan tool?

**1slowbusa** · 03-24-2013, 08:56 AM

Originally Posted by 383ls6

do you have access to a scan tool?

Yes, i have HP tuners and VCM Scanner. The car runs smooth with no knock. I have tried to make knock as recommended by a tuner i talked to and see if KR activates and it does, so that tells me that the knock sensors are working. I really think that they are picking up false knock but I do not know how to tune the knock sensor and I have not seen any write up. I do not want to just disable them.

Do you know a way that I can check to see if the knock sensors are functioning correctly? Do you know how I can tune them?

**pajeff02** · 03-24-2013, 10:34 AM

In HP Tuners, there are tables for tuning the knock sensors. It appears that Frost adjusted mine as part of the mail order tune. Settings are under <Engine>, <Spark Control>, and then <Knock Sensors>. You will then see tabs for setting both the level and gain.

**1slowbusa** · 03-24-2013, 11:38 AM

Originally Posted by pajeff02

In HP Tuners, there are tables for tuning the knock sensors. It appears that Frost adjusted mine as part of the mail order tune. Settings are under <Engine>, <Spark Control>, and then <Knock Sensors>. You will then see tabs for setting both the level and gain.

I have the mail order tune from Frost and i did a compare and he changed the knock sensor data in the new program. Please keep in mind that i would never say anything bad about Frost because when the code is not on, the car runs great. Its just this code that is giving me the problem. Every troubleshooting guide I have found and performed, the knock sensors are working correctly.

**383ls6** · 03-24-2013, 05:19 PM

sorry man didnt realize you had a tuned pcm. thats over my head. post up when you get it figured out.

**1slowbusa** · 03-24-2013, 05:47 PM

Originally Posted by 383ls6

sorry man didnt realize you had a tuned pcm. thats over my head. post up when you get it figured out.

will do. Thanks for your support.

**Mr_Rich** · 03-25-2013, 10:16 PM

Did you back probe the leads to get those readings? Not the way to do it. Make it simple for yourself. The knock sensors on my '98 read 1000 ohms resistance. When I installed my intake on the new engine almost two years ago I pinched the harness on one of the nubs of the valley cover. I had 0 ohms on the front KS and 1000 ohms on the rear KS. Quite a few people have done it besides myself. I unplugged the harness and set the meter to the resistance setting and checked the KS terminal at the plug to ground. I had Weatherpak connectors and fixed the harness myself. No problem since.