cthree

Has anyone with a DL1 or other logger tapped into the stock sensors? The ones I'm looking at are RPM, brake and clutch switch (from cruise control), throttle position, water temp, oil pressure, MAP, intake air temp and so on.

If so can you please post which wires you tapped and where you connected them? I don't have the electrical manual and the standard service manual only briefly mentions these.

Raymund

ECU
For RPM tap on the RPM signal indicated above. The TPS pin looks tempting. If only it was that simple..

davepk

There is a loose black wire in the engine compartment right next to/ underneath the brake master cylinder that provides the RPM signal.

Its what i used and i think its what Honda uses in their diagnostic equipment.

jzr

I hooked into the TPS sensor on my 240sx and it works great. Most car's sensors are either 5v or 12v, the FSM should tell you which, so you can use the appropriate port on the DL1.

You guys should look and see if there's a steering angle sensor somewhere in there, that's a fun one too.

jlucas

I'm working on a more formal document with pictures and coupler illustrations but this is the short version:

RPM - blue wire out of the ECU (A19)
Clutch switch - pink wire into cruise unit (14); to the left of the ECU
Coolant temp (MTRTW)- yellow/green wire out of the ECU (A1)
Throttle Position Sensor - red/black wire on the ECU (C27) 0.3v fully closed, 4.8v fully open (never really closes below 6% according to the manual)

2006 cars may be different than listed above, I haven't looked at those yet.

2006 cars should have a steering angle sensor for the VSA but I don't know what the output looks like.

cthree

Thanks guys!

I did eventually find the ECU wiring diagram in section 11 under Fuel and Emissions. What I have is:

MAP C17 (GRN/RED) 5v Manifold Absolute Pressure (?)
TPS C27 (RED/BLK) 5v Throttle Position (0.3V full close, 4.5V wide open)
VTS B12 (GRN/YEL) 5v VTEC Solenoid (on and off)
NEP A19 (BLU) 5v Tachometer (goes under the hood to test connector as davepk said, pulsed I think)
IAT C25 (RED/YEL) 5v Intake Air Temperature (0V -> 150C, 5V -> -20C)
ECT C26 (RED/WHT) 5v Engine Coolant Temperature (same as IAT)
VSS A9 (BLU/WHT) 5v Vehicle Speed Sensor (pulsed)

In addition there is a clutch pedal switch and a brake pedal switch which connect to the cruise control unit and the 4 ABS wheel speed sensors at each corner terminating at the ABS control module. I haven't looked closely at these and I'm not sure if I can use the wheel speed sensors on the DL1.

jlucas

I wouldn't bother with VSS, as your GPS speed will be more accurate.

For the benifit of others (to elminate confusion). The ECT (C26) wire you list is from the sensor to the ECU, the one I listed MTRTW (A1) is from the ECU to the gauge cluster. I have not logged either of them so I don't know if you'll see a difference between the 2.

The White/Blk wire going into the cruise control module (5) is the brake switch depressed circuit.

ellisnc

It should be directly on CAN so you'd need either some box to translate it (and the address) to an analog input or Race Tech needs to make a CAN module.

ellisnc

What do you hope to see by looking at wheel speeds? Just curious...

The problem with running a bunch of sensors from different control units into data aquisition is that you have a bunch of different ground points. So either you don't ground them all together and get some strange offsets or if you do ground them together you can get noise on signals that wasn't there before based on whether the ABS motor is running for example.

How many signal grounds does the DL1 have?

cthree

It has 2. All of the stock sensors are grounded together in the ECU. I didn't say there was any real advantage to tapping the wheel speed sensors only that it could be done if one wanted to. This thread is not only a discussion of sensors but hopefully will serve as a reference for the future in case anyone else wants to do it.

I have tapped the RPM and TPS sensors and they work flawlessly (well almost) and I also tapped the VTS signal but it doesn't show up in the data, must have goofed. I got a problem with the RPM signal in that now the tach in the dash only works if I have the DL1 connected and plugged in, doh! I'm sure I can fix that up soon enough. The RPM data is cool because it shows when and at what RPM you shift and you can see if it was short or not (not obvious from other data alone). It's a handy input to have.

The TPS data is awesome! This is even better than the RPM data. It not only shows when you lift but by how much. It really helps to know when you got on the gas and how smooth you were. Looking at my data from yesterday I notice that in one corner getting on the gas hard and early was actually slower than getting on slower. I think what was happening was I was applying too much throttle in the corner to fast and causing the car to push and compensating with steering input. It was a downhill corner. On the laps where I held the same line but had smoother throttle input I had quicker exit speeds. Very cool. Some other cool things the TPS tells you: throttle blips, did you heel-toe? did you let off? did you let up at some point in the corner? were you pumping the throttle or was the application smooth and steady?

I'm not sure that the engine sensors will tell me much from a driver standpoint and have put off connecting them. I think at some point I'd like to install a steering position sensor because that data I think would be as useful as the TPS.

One thing the wheel speed sensors might tell you is wheel slip but for me I think it might be TMI unless someone else can tell me otherwise.