Wiring for M142 ECU

[shantim]

Hello Everyone!

I am currently connecting the Motec M142 ECU to my engine and therefore, I am doing the wiring. Only C and D connectors of the ECU can be used since wiring has only those two connectors. I have following doubts regarding the same:

1. For Hot film air mass sensor, there are four wires: Supply, Ground, Air mass flow signal and Air temperature signal. Which of the pins in the ECU can be used for air mass flow signal?

2. There are some position sensors also like EGR position sensor and Intake throttle position sensor. Which pin of the ECU C and D connector can be used for position sensor?

3. For TMAP or Intake manifold pressure and temperature sensors, can the temperature signal be connected to any of the analog temperature input and pressure signal to any of the analog voltage input? or do I need to ensure something?

4. For actuators, such as the EGR valve, can it be connected to any of the half bridge output?

Please guide me regarding this as soon as possible.

Thankyou.

[Stephen Dean]

Why do you not have the A and B connectors? These ECU's are designed around having all of the connectors in use, especially the Power and Ground supplies so not using them for more than a short period of time can lead to damage to the hardware.

1, Depending on the MAF sensor signal, usually a UDig is needed, but some will output a Voltage signal, which is wired into an AV input. The MAF signal is not used for tuning in the M1, just for information. The Temp signal will go into an AT input.

2, Throttle Position maybe into an AV input, or a Sent input which uses a UDig input. EGR most likely will be into a AV input.

3, The AT inputs are internally linked to 5V rails through 1k pullup resistors, because of this, you need to match them to their corresponding 0V buses, with AT1 & 2 to 5VA, AT 3 & 4 to 5VB and AT 5 & 6 to 5VC. Otherwise you can use any available AV and AT. If you are wiring in a TMAP sensor, make sure that the 5V supply used matches the 5V supply for the AT input that you are using.

4, Some actuators that are driven in both directions (DBW throttle for example) need to be wired to a Bridge output, this is done by wiring the actuator to the paired Half Bridge outputs, i.e. Bridge Output 1 consists of Half Bridge 1 and Half Bridge 2. If you allocate HB1 to a different Function, then Bridge Output 1 will not be available.

[shantim]

Dear Sir,

Thank you so much for your reply.

I have some more doubts regarding the wiring. Firstly, the wiring that we are using has part number 61236, Revision C and Data Code: 1903260200. It has two connectors (34 pins and 26 pins). These two will be connected to M142's C and D connectors only. For connecting to A and B connectors of M142, an additional wiring harness set will be needed but since we have limited sensors and actuators, we can accommodate them in the C and D connectors. Therefore, we are not using the A and B connectors. The Power supply (Battery Positive) will be connected to C26 and the ground supply (Battery Negative) will be connected to C10.

Furthermore, regarding the AT1, AT2, AT3 and AT4 inputs, I checked the wiring harness and AT1, AT2, AT3 and AT4 correspond to the D3, D4, D5, D6 pins, respectively. In the wiring, the inputs have been taped to the ground wires or supply wires by default (got as it is from the seller). So, on checking I found that the ground wires taped with all four of these AT inputs had one common source (black wire) that corresponds to pin D16. And on the Motec website, the M142 connector D's table lists the D16 as Sensor 0VB. However, as you said that the AT1 &2 should have different ground wire from that of AT3 and 4, but they all have one common source, 0VB.

Also, I checked the wiring for all the analog voltage wires and found that all of them have been taped to a common red wire as supply which corresponds to pin C2 (Sensor 5VA) and a common black wire as ground which corresponds to D15 (Sensor 0VB).

So now for connecting the wires of TMAP sensor can we connect them as:
Temperature Input : D4 corresponds to AT2 with 0VB as ground wire
Pressure Input: C14 corresponds to AV2 (has 0VA as ground wire but this ground will not be used)
Ground : Black wire that is taped with AT2
Supply: Red wire that is taped with AT2

Please let me know, if this seems correct.

Thankyou.
Sincerely,
Shanti

[shantim]

Dear Sir,

Thankyou so much for replying. I have some more doubts listed below:

1. Can we connect the 12 V output from the Main Power Relay (of the stock ECU) to the C26 pin of M142 ECU and then give the 12 V supply to the actuators through the same C26 pin?

Battery positive to Stock ECU main power relay- 12 V output to C26 pin of M142
Battery negative to C10 and C11 of M142

Wiring of actuator for e.g: Inlet Metering Valve: 12 V supply - C26, Output Signal - C34 (Half Bridge output 6)

2. As you said that AT1 and AT2 should be internally linked to 0VA and AT3 and AT4 to 0VB. But in the wiring loom Motec Part No: #62207, I found that the AT1, 2, 3, 4 are all linked to 0VB (the wires are taped together for example D3 corresponds to AT1 and two wires orange and black are taped together, orange corresponds to D3 (AT1) and black is D16 (0VB))
Also, all the analogue voltage outputs are linked to 0VA.

so for TMAP sensor, the wiring : supply - C9 (5VB), Pressure signal - C15 (AV2), Ground - D16 (0VB) and Temperature signal (AT2), does this seem correct?

Thankyou in advance!
Sincerely,
Shanti

[Stephen Dean]

Hi,

61236 is the Ethernet cable component of the loom, not the complete loom.

62207 is a cut to fit loom designed for use with the M130, and isn't suitable without changes for use with the larger format ECU's such as the M14x. The 0V and AT groupings have to be resolved in this loom as that isn't how they are supposed to be done. In normal operation this will not cause issues, it is only if a sensor fails and affects the Voltage supply that having the correct 5V and 0V is required.

Using a large form factor ECU, all of the Batt+ and Ground supplies MUST be connected, failure to do so, especially with DBW and Direct Injection, will result in damage to the ECU.

Voltage supplies for actuators, coils and injectors ideally should come from the same source so that any voltage compensations needed can be applied correctly.

That is correct for the TMAP being used on an M130, for all other M1's if you are using AT2 for the input for the Temp sensor, then you need to use 5VA as the voltage source as AT1 and AT2 are internally linked to 5VA (AT3 and AT4 to 5VB) in the large form factor ECU's