I thought it would be nice to have a small LED light inside the dash to alert me of when the Knock Module detected true knock, trying to watch a laptop doesn't work. The problem is where do you pull the signal from the module in the ECU? I've spent hours searching and no one has apparently done this mod..

Any ideas or diagrams?

 

There is no output from the PCM, other than diagnostic readout, that I know of. Not saying it can't be done, but you aren't going to find a pin with any output signal.

 

Unfortunately, there's no one pin you can tap to indicate there is knock being picked up. The knock sensors are like microphones, and they send similar analog signaling to the PCM. The PCM then converts this data (via the knock module) to digital data. Once it becomes digital data the PCM's microcontroller would run some code that processes this to determine if there is knock, or not.


Having said that, knock retard is one of the pieces of information available during runtime via the diagnostics port (Datastream 276, Mode 1, Message 0, Byte 52) which means datalogging software should be able to pick this up for you.

If you see any knock retard at all, this means the PCM believes there is true knock based on its signal processing.

 

so there is no way of seeing when the computer senses knock or than datamaster or another laptop datalogger (or scanner tool)?

 

Not easily. You'd have to find somebody that knows intricate details of the internals of the PCM. It's unlikely that anybody outside Delphi or GM has that kind of knowledge.

Why doesn't using a datalogger work in this situation?

 

Beucase i want it for when i'm driving. Its going to be put on a procharged daily driver stock LT1... so knowing if i have any knock MIGHT help prolong the motor long enough for me to finish my spare motor thats being converted to fully forged.

 

Gotcha.

The common approach towards resolving this concern is to do enough dyno tuning to be sure the tune is close enough such that there wouldn't ever be any knock.

However, if you want to monitor this on an ongoing basis you could use a datalogger and review the files after each drive until you were sure there wasn't any knock problems. Alternatively, there some at least a couple companies that sell a stand-alone knock sensor and readout. I believe the F-body cars used only one knock sensor, but I know the Impalas used two. This means the F-body engines should have a provision for installing a second knock sensor on the opposite side. You could purchase one of these kits and monitor the knock status through the readout.

Or, a savvy electronics guru could build a fairly simple device that plugs into the diagnostic port and constantly polls the datastream (the same one dataloggers use) for knock retard data and display an indicator light if any is detected (I see a good product idea in here, somewhere). ;-)

You could also look into using an aftermarket PCM.

 

Check out MSD part #8964 (http://store.summitracing.com/partde...5&autoview=sku)

 

The knock sensor can't distinguish between true knock and false knock.

The LT1 Scanmaster will not only display that you have knock, but also the "degree" of knock.

 

Thats nice and all, but i just want an LED light for in the dash.