Knock Sensor Disconnected Faults on Haltech Nexus R3, with connected sensors.

This is my first post here, I've been digging for answers for about a week while on a work trip and scoured this site, others, talked to friends, and came home to troubleshoot my system only to be stumped. I have more questions than answers now, here goes. I have a 93 Supra, 2jz GE-T, running a Haltech Nexus R3, Haltech Flying lead harness, and PD16. It's back on the road, running and driving but I have Knock Sensor Disconnected fault codes P0328/P0332, and nothing else.

I have confirmed proper pin location at connector C, pins 23,24, and have continuity to each knock sensor, the same for sensor ground to C26. Drag testing the terminals in the sensor on the pins is satisfactory, and I have connected a meter to the knock sensors and can generate voltage spikes when tapping it. So the wiring is good, the terminations are good, pin locations are correct, sensors work. I haven't voltage drop tested the circuits, but am certain the crimps are good, and the knock sensors are straight runs in jacketed and shielded legs to the ecu. The sensors are mounted to bare metal on the bosses and torqued just for funsies to see if it made a difference. With the knock sensor unmounted but plugged in and the engine running I can tap on it and register nothing in the ecu.

The knock sensors are AC Delco PN#12600327 ( which also runs as Bosch part numbers) and these were on the engine when the ecu was an ECUMaster Classic, and they worked. On the Sensors>Knock Detection>Wiring page when the engine is running both sensors are showing -32dB or so, uniform and revving the engine sees these values climb, but see nothing on the spectrometer, scope etc. I'm completely stumped. Am I dealing with something as silly as these ecus requiring a specific knock sensor? Did I miss a setting? (I am rather new to this ECU platform )

Thank you in advance for any insight you can give me.

Check that there is no continuity from either knock sensor pin to the mounting base, some of the bosch sensors have 1 of the pins tied to engine ground which may upset whatever test they are performing to trip that fault code.

If that looks ok then it sounds like one to bounce of Haltech.

I did perform that test and there is no continuity to the housing from either pin, but now that you say that I wonder if that's what it's looking for and can't see it. I did message Haltech about this but hadn't heard back for a few days, I may call over there or pop on the forum. Thanks for the input, there just might be something to this.

For an update to this, I got an RMS to send the Nexus R3 into Haltech. I put my scope on the knock sensor signal pin and confirmed the sensor is generating a signal and it’s making it to the pin, but the ECU isn’t doing anything with that signal or receiving it internally. I haven’t marked resolved yet because I want to await confirmation from Haltech but all fingers point to a faulty ECU. We will see.

Subscribing to this post, as I’ve had the same issue on mine. I keep getting knock sensor disconnected, and as far as I can tell the sensor and the wiring are all OK. I may bite the bullet on my next check and order some knock sensors from Haltech, as I’m not 100% certain that my sensors are legitimate Bosch units.

I don’t think it’s the sensors man. In the event that they did have an oddball sensor with an internal resistance between terminals, I looked up variations and found the nominal value and jumped terminals to cheat that validation with a 100k resistor, it had no effect, which I didn’t expect for a 200mv bias signal. I also spent a LOT of time digging, about a week while traveling, and found zero reference to there being specific knock sensors required aside from being non resonant for an r3. If there were I’d kinda expect to be called a n00b on resources like this instantly with the collective knowledge and experience here.

Mine has to be sent in regardless due to the log file issue. I’ll know for sure soon.

It sounds like, on yours at least, that everything is fine with the sensors and wiring. I'm wondering if anyone else with a Nexus has had similar issues. I just submitted a support ticket with Haltech.

Do you have any data logs from when you're getting the error? I wouldn't mind checking the data to see if it's reading similar to mine. Mine is happening on sensor 1 more than it does 2, but it still happens on both, and it's reading negative Db values on sensor 1, with low to negative readings on sensor 2.

I'm attaching one of mine if you want to look at it too. It's not letting me upload the full PC log file for some reason though.

My ECU is incapable of generating log files, but monitoring the channels with the native scope function shows nothing. On the configuration page, while idling both sensor circuits float around -32dB and rise but never above the teens and they're dead even.

You should still be able to generate a PC log file by using the laptop to record. The hot-key for this on the NSP software is F6, and F7 to stop, or shift+F7 to stop and open the file in datalog viewer.

Looking back at mine, they're doing something similar to yours, in that they're reading negative dB values. I'm waiting on a response from Haltech now too, but I'm going to try to get some time to test a few things this week. I'm wondering if the frequency that I have entered is correct. I've done the math several times, and I get the same results every time. However, my thought is, if I'm listening on the wrong frequency, it may be filtering the signal out as "background noise", thus giving me a negative dB value. I'm just speculating though, at the moment.

That's what I'm saying, lol, one of the problems with my ECU is it cannot generate log files, they're always corrupted and crash whether on my PC, or my Tuner's laptop. I just opened yours and see what you mean. On Knock #1 you've got about 1:30 of Background noise that's got a range of about 15dB but all negative and that eventually drops away, no Instantaneous voltage, and no Signal, but your Knock #2 is strong on all counts and holding about 2.17v avg. You said it's doing this intermittently?

The thing about the -dB value is that isn't a negative value per se, it's just frequency too low for the human ear to hear but still has a voltage value associated with it. I messed around with changing the knock frequency like you're talking about and it had zero impact.

It's intermittent on Sensor 2, but I don't think I've ever had sensor 1 work. I've gone through all of the same steps you have, changed the connector, and they're brand new sensors.

As far as your datalog issue; have you made sure it's on the latest firmware? I did have an issue at one point with O2 control not activating due to a firmware bug. I haven't read all of the patch notes, but I think I read something at some point about data logging issues being an item that was patched on the Nexus VCUs.

Yes. just for grins, when did you buy your Nexus?

I ordered mine about 4-6 weeks after the initial release of the R5. However, my first start with it in the car was about 10 months ago. I've been dealing with lots of mechanical issues that need to be sorted out before I hit the dyno, and South Texas heat has made it tough to want to get under the car with no garage to deal with them. Not to mention the seemingly endless honey-do-list keeping my weekends busy. But, I'd like to get this knock sensor issue sorted before I hit the dyno, because I don't have another way to reliably monitor for knock.