Knock sensor

p150rulz · 03-09-2006, 01:41 PM

I've been told that my knock sensor wire was re-routed wrong when I had my transmission rebuilt and it somehow got wrapped around the axle and has messed up the wire. What would be some symptoms if this was messed up?

BNaylor · 03-09-2006, 01:49 PM

Quote:

Originally Posted by p150rulz

I've been told that my knock sensor wire was re-routed wrong when I had my transmission rebuilt and it somehow got wrapped around the axle and has messed up the wire. What would be some symptoms if this was messed up?

You should get a DTC error code or maybe nothing since the wire is open.

The knock sensor only works when detonation is sensed by the PCM knock sensor module via the KR sensor mounted on the block. There are two. One fore and one aft on the engine.

richtazz · 03-09-2006, 01:55 PM

DTC codes p0325-p0334 pertain to the knock sensor, so I would think one or more should show up if the circuit was open or shorted.

BNaylor · 03-09-2006, 02:00 PM

Quote:

Originally Posted by richtazz

DTC codes p0325-p0334 pertain to the knock sensor, so I would think one or more should show up if the circuit was open or shorted.

Not really Rich, it is a weird circuit. Some sensors do not do squat when open. The KR module in the PCM needs a positive level voltage to activate and retard ignition. If he has SES light I believe he would have mentioned that. Is there an SES light? KR is a class "A" DTC error code meaning it will trigger SES/CEL mil light.

BTW - I recall he has a GTP.

p150rulz · 03-09-2006, 02:15 PM

I haven't looked at the codes or anything, but would this cause some shifting or timing problems?

richtazz · 03-09-2006, 02:28 PM

It could if the open circuit causes the PCM to read that there is knock present. When the PCM detects knock, it will retard timing to compensate.

BNaylor · 03-09-2006, 03:04 PM

When monitoring the knock sensors #1 and #2, the PCM is supposed to trigger either P0327 for # 1 or P0332 for # 2 if it detects low voltage which we assume an open will give. It should trigger an SES Mil light after two consecutive trips or drive cycles.

The parameters to set these DTC error codes are:

*No active throttle position or ECT sensor DTCs.
*ECT (engine temperature) must be above 149 degrees F or 65 degrees C.
*Engine running at least 10 seconds.
*TP (throttle position) angle must be greater than 1.5 %.
*Engine speed is 2500 - 2900 rpms.
*Difference between KS minimum learned noise and noise channel is less than .4 volts.

In certain circumstances when P0327 for # 1 or P0332 for # 2 set, the PCM will make a decision not to retard any ignition timing due to the detected malfunction. Instead it opts to trigger those codes to let you know something is wrong, which makes sense.

BTW - Don't ask me why it operates that way, it just does. I'm simply explaining how the circuit works.

richtazz · 03-09-2006, 03:21 PM

Nice write up Bob, of course my head hurts now

and I need a nap,

but still a nice write up.

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