P0327 Knock Sensor Low Circuit Voltage [Archive] - GrandAmGT.com Forum

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eckoxl
06-12-2011, 12:27 PM
I am at a loss with this right now...

I've replaced the sensor, cleaned the threads & the connector no luck. The only thing I can think of that would be causing it would be how I grounded the engine to body ground or how I grounded the negative terminals to the body when I moved my battery to the trunk.

Anyone have any insight on what else could becausing this? I'm going to redo my grounds because currently they aren't on unpainted metal, so Im going to grind it down to bare metal and go from there.

Any help would be appreciated.

HOYS
06-12-2011, 01:16 PM
Did you clean the threads in the block?

eckoxl
06-12-2011, 01:30 PM
I've replaced the sensor, cleaned the threads & the connector no luck.

I think I'm just going to run a ground wire from the battery to the front. Where does the ground on the block get bolted to? I forgot where it went when I put the engine back in last year.

eckoxl
07-19-2011, 12:06 PM
Bringing this back to life...

I've rewired all my ground in the car and I'm still having this issue.

Here's how my grounds are run, all being 4 gauge wire:
- wire from batter neg to dist. box under hood
- dist. box to chassis, stock location
- dist. box to trans ground next to the mount, stock location
- dist. box to top of trans, then there are two 8 gauge wires tap tap off from there and bolt onto each head

The only stock ground that I don't have is the direct engine to chassis, but technically the two trans grounds going to the dist. box then then dist. box to chassis would make up for that, correct? Or are our cars just that picky that they have to have it? Maybe I should make the ground directly on the engine block then to the chassis? I'm at a loss here. lol.

AleroB888
07-19-2011, 11:12 PM
Bringing this back to life...

I've rewired all my ground in the car and I'm still having this issue.

Here's how my grounds are run, all being 4 gauge wire:
- wire from batter neg to dist. box under hood
- dist. box to chassis, stock location
- dist. box to trans ground next to the mount, stock location
- dist. box to top of trans, then there are two 8 gauge wires tap tap off from there and bolt onto each head

The only stock ground that I don't have is the direct engine to chassis, but technically the two trans grounds going to the dist. box then then dist. box to chassis would make up for that, correct? Or are our cars just that picky that they have to have it? Maybe I should make the ground directly on the engine block then to the chassis? I'm at a loss here. lol.

Why not run a new KR signal wire directly to the PCM? Dark blue wire, Pin #33, Blue connector (other connector is clear color).

eckoxl
07-25-2011, 11:02 PM
The light has been going on and off the past couple of days. I'm going to get a new sensor, again, then test with a volt meter. I really don't want to have to rewire it, but we shall see.

...

Another issue I want to bring up in this thread just because I also think its a ground issue or some kind of electrical gremlin...

Everytime I turn on my parking lights and/or headlights, the abs light will come on. Any ideas on that?

plastic_indian
07-26-2011, 01:40 PM
Another issue I want to bring up in this thread just because I also think its a ground issue or some kind of electrical gremlin...

Everytime I turn on my parking lights and/or headlights, the abs light will come on. Any ideas on that?

I once forgot to plug the alternator connector back in following an intake job on an N car. During the test drive the ABS light came on - the code set was for low voltage. I've not personally had a KS low voltage code as the only symptom in a low system voltage situation, but I suppose anything is possible. Switching on the lamps could be sufficient load to cause the (apparently) voltage-sensitive ABS/traction system to get upset. If basic electrical is ok, I sure wouldn't blame a fella for spending a few minutes looking over the ground points, especially G102/3/4/5.

eckoxl
08-28-2011, 12:35 PM
bringing this back to life...

still getting the knock sensor coded every once and a while. on thursday i put in another new sensor then me and stewartfn20 did some scans and the kr will not go above 9.83 (yes i know that is bad). think the wire is bad?

sleepyalero
08-28-2011, 12:54 PM
it might be bad..

eckoxl
01-08-2012, 01:55 PM
Bringing this back to life... again...

I have ran a new wire directly from the PCM to the sensor and still no luck. I've also tried putting some dielectric grease on the threads to see if that would help. I need to get this problem solved as it is messing with my tune. The only thing I have left is to clean the block threads; my block is powder coated and even though they said the threads weren't coated, I'm going to sand them to bare metal and see if that helps. Anyone else have any other suggestions? I am at a complete loss.

HOYS
01-08-2012, 02:27 PM
IIRC the threads have to be bare metal for the sensor to work. Tap the hole and you should be good to go.

If this does not work, get a new PCM.

eckoxl
01-08-2012, 02:47 PM
Alrighty, wouldn't happen to know what size the threads are?

AaronGTR
01-08-2012, 04:52 PM
iirc they are pretty large, and might be a fine thread pitch. It could be difficult and/or expensive to find a tap that size, and it might have to be mail ordered too if no stores carry it. You'd have to take one of the sensors with you somewhere to compare threads.



Also, don't know if you've considered this yet, but... if you clean up the threads, have tried multiple new sensors, checked and replaced the wiring and connectors already... then there's a possibility it could actually be the PCM itself.

AleroB888
01-08-2012, 09:04 PM
and as long as we're reaching for answers........

I don't know the internal schematic of the PCM, but find out if the K sensor relies on a reference voltage. For instance, there is a 5 Volt REF voltage for some of the sensors. It is possible another sensor is bad, and affecting the REF voltage. I mention this because I once had a bad TPS, but instead the PCM registered only a "low REF voltage" code, and the fuel level gauge dropped to zero.

AaronGTR
01-09-2012, 04:44 PM
and as long as we're reaching for answers........

I don't know the internal schematic of the PCM, but find out if the K sensor relies on a reference voltage. For instance, there is a 5 Volt REF voltage for some of the sensors. It is possible another sensor is bad, and affecting the REF voltage. I mention this because I once had a bad TPS, but instead the PCM registered only a "low REF voltage" code, and the fuel level gauge dropped to zero.


I don't think that's the problem. Checked my manual and there is one diagram for "engine data sensors", many of which have 5v reference. It includes the A/C pressure sensor, TPS, fuel tank pressure sensor, MAP sensor, ECT sensor, and IAT sensor.

The next page is a schematics for main power and ground, with the cam position, 24x/7x CPS, knock sensor, and ICM wiring. The knock sensor only has a single wire (dark blue) for the knock sensor signal to the PCM.


Also, here is a bit of interesting info. My manual does not call that code P0327 "low circuit voltage". It just calls it "knock sensor circuit". In the description it says...

"An input signal from the KS is used to detect engine detonation, allowing the PCM to retard ignition control spark timing based on the amplitude and frequency of the KS signal being received. The KS produces an AC signal under all engine operating conditions. During engine operation, the PCM calculates the average voltage of the KS signal. If the knock sensor system is operating normally, the PCM will see KS signal voltage vary above and below the calculated voltage average. If the PCM detects KS input signal equal to the KS average voltage over 95 % of a calibrated time, DTC P0327 will set."

It sounds to me like what they are saying isn't that the signal voltage is low, but that the activity is low. IE it should be going up and down sort of like the O2 sensor signal does. You get a similar code if the O2 sensor doesn't vary enough for "insufficient activity".

Malaclypse
01-09-2012, 05:52 PM
^What Aaron said.

The PCM tests the knock sensors by deliberately inducing some knock and reading the signal created by the knock sensor.

The knock sensor itself actually creates A/C voltage when it senses vibration. So if you can see the knock sensor voltage or activity parameter, try monitoring that and tapping on the engine block lightly with a hammer. It should pick up signal.

If the sensor is indeed reading a signal and the code is still setting it may be an internal PCM problem. Try replacing the wire to the sensor itself first, obviously... and make sure that the pin inside the sensor isn't bent over to the side. I've done that before.