RomRaider

I need the PWM throttle position output signal for an ABS ECU (not ASC), but it doesn't seem to be outputting (the ABS ECU says no signal). Is there a control bit or other coding that needs to be done to make sure that the signal is output?

It's the DKI signal, pin 45 on the X6000 DME connector.

I don't have the other ASC wires connected. Does that matter?

I have an S52 running a 2000 Z3M DME with ZB number 7830287. Those came with ASC as far as I know. I have another DME with the standard E36 M3 tune on it, ZB number 1407136, but I haven't tested that signal to see if there's a difference.

I tested the throttle position output signal from the DME with a multimeter and I confirm there is no signal being output. I also tested the TPS on the engine and it’s good. INPA also shows the signal is being received from the TPS.

The only thing I see on the coding side for it is the ASC setting (Control bit 0 on Byte 7). The value for Byte 7 on the DME is 9. So bit 0 has value 1 for ASC enable. User mrf582 stated that bits 1 and 2 might be related (in the Control bits thread) and he said they might correspond to the other 3 ASC connections on the DME. I don’t see any confirmation on the forum, but he repurposed those connections for other things with MS41.3. I’m thinking he must have figured it out. So are those 3 connections not dependent on control bit settings and still function without an ASC module?

That brings us to a mystery with the TPS output signal. Is it dependent on an ASC module being connected? Does the DME require a request on one of the other 3 ASC connections in order to output the signal? It makes more sense to me that the ASC module would not make any requests without knowing the throttle position to begin with.

I could try toggling bits 1 and 2 on Byte 7 to see if there is any effect on the TPS output signal. I could also try toggling bit 0. Any other ideas?

I'm reading that the 3 ASC connections, S-EML, S-ASC, and S-MSR, are switched high/low signals. I'm also reading that when those are repurposed with MS41.3 those can be toggled with 5 volts. So, in their original use they are 0 volts (low) and 5 volts (high)? Or ground (low) and 5 volts (high)?

If I apply 5 volts to one or all of those would it make the DME think that the ASC module is present? It seems like that would be the case. I'm trying to figure out which pins those are (80, 81, and 82) and it looks like S-EML is pin 81. It appears that S-EML only controls the ASC throttle valve. The other ones affect injection and ignition timing, so I don't think it would be a good idea to have 5 volts on those all the time. So perhaps applying 5 volts to pin 81 would make the DME output the throttle position signal.

However, according to the ASC document 34 01 93 (2136), the low signal is normal, so either 0 volts (or ground?). So it might be best to provide a momentary voltage to pin 81 when the ignition is switched on, but since the ASC unit isn't there perhaps it doesn't matter.

Nevermind lol. I was wrong. The DME does output the throttle position signal regardless of the ASC module being present. I tested it again with the multimeter as I pressed down on the throttle pedal.

So the issue I have is on the ABS ECU side. I've retrofitted ABS to the Land Rover Defender 2.8i and the ABS ECU is new. It either doesn't like the signal or it's not configured correctly. That ABS ECU came on the Defender Td5 and early Puma models (Wabco D). According to the Land Rover documents the Td5 ECU outputs a PWM throttle position signal to the ABS ECU. I can look at the realtime data using a Faultmate MSV diagnostic interface and it shows nothing for throttle position. You would think it would show something even if it's not exactly what it's looking for. It also doesn't show the engine speed, so that signal might be different between the TD5 ECU and the MS41 DME also. I'll have to research the Land Rover side of things.

Perhaps the signals just aren't compatible. So I may have to live without traction control. This is what the Td5 Electrical Library document says:

"The ECM provides the ABS ECU with a Pulse Width Modulated (PWM) signal on an
SP wire. This signal includes information on engine torque, engine throttle, engine
type, and throttle type."

"The ECM provides the ABS ECU with pulsed voltage signal on a YK wire. This signal
informs the ABS ECU of engine speed. The ECM provides the ABS ECU with two
voltage pulses per engine revolution."