The Mitsubishi Pajero Owners Club®

[J.W.]

Hi.

Anyone on here have a pinout for a engine ECU (MR577140) for a 4D56 engine in a pajero sport?
The pajero sport is a 2006.
My issue is when I turn on the ignition I get all the usual dash lights but not the engine management light or the glow plug light. I changed the ECU but still the same.
Any suggestions on cause welcomed.

Thanks,
J.W.

[Google]

[iam_TJ]

Did you confirm the bulbs in the binnacle are not faulty, and that the binnacle connectors and associated FFC (Flexible Flat Cable) and wires are all good?

[J.W.]

Hi Tj.

I did not get that far. I was hoping to test these from the ECU harness side if I had a pinout for the ECU and I could then also check all the ECU supply Voltages and grounds with confidence.
The car is not starting either I should mention.

Thanks,
Jason.

[iam_TJ]

Aha! So a bit more going on and quite serious. First thought is possible immobiliser problems, but it'd probably be best if you describe exactly what does and does not happen during the start-up sequence and what tests and diagnostics you've done. For example: what fault codes are reported, have you tried a spare key, does the starter motor turn?

[J.W.]

Don't think it's immobiliser problem as I changed the engine ECU and immobiliser ECU and the immobiliser antenna but still no joy.
The diagnostic tool isn't seeing the engine ECU but can see other modules when plugged in (have to borrow the diagnostic tool as I dont have my own so from memory i cant remember which other modules it picked up.)
I've checked the power to the Engine ECU and the grounds that I know of and they seem ok. I suspect a power issue cos it is like the ecu isn't powering up. Having tried a second ecu I don't suspect the ecu is the problem.
The only thing that I can see is different when I turn on the ignition is the check engine light and the heater coil lights do not illuminate. All other dash lights do appear. Then when the key is turned to start, the engine cranks but never starts. I opened an injector while cranking the engine and no diesel came up. So the pump is not getting a signal to come on either.

[iam_TJ]

I was originally trying to help you with the circuit diagrams since I have the workshop manuals for the Pajero Generation 3+facelift (2001-2003-2006) some of which have the same 4D56 engine and therefore possibly a very similar ECU, but I had to give up after an hour because I could not identify a Pajero/Shogun model code which has the 4D56 engine, and to look up which part numbers it uses on megazip - which uses only the model codes to identify vehicles.

From simply searching the part number it only lists models in the K94W series: GNHFL6, GNGFR6, HUFL6, NUFR6.

https://www.megazip.net/zapchasti-dlya/mitsubishi/control-unit-eng-MR577140

However, someone else here recently suffered an ECU fault which they diagnosed as a hairline crack across the PCB but your swapping in an alternate ECU suggests (unless the alternate is also faulty) that as you suspect, the ECU is fine.

Therefore, by following a process of elimination, and with a basic multimeter than can do continuity tests, you ought to be able to at least reduce the possibilities. It requires being methodical and keeping clear records of what has been tested, expected and actual results, but if your time is available that is the only cost.

To guide me I've found an ebay listing that is apparently the same MR577140 ECU so I can see the pin-out configuration at least.

I'd start by carefully examining the 4 connector blocks and ensuring that every wire entering is connected to a terminal. I'd also attach a long fly-lead to one probe of the multimeter and try to detect incoming +V and ground at each terminal of each connector by connecting the flying end to the battery terminals or a known-good chassis ground.

I say this since last year I had an issue on a Nissan Primera that would not start or even turn over; professional garage mechanic couldn't figure it out. Starter motor operated when connected directly to battery. With the aid of a circuit diagram I followed the connection from the ECU through the ignition switch to the starter motor. Behind the glove box was a junction (connector) on the wire; one spade terminal 'wrist' had snapped completely and the wire was hanging free. All it needed was a new spade terminal soldering on.

You may even be able to deduce (some) power circuit wires by their thickness - signal wires don't require much current so may be thinner/ have less strands).

In the Pajero/Shogun the workshop manual has a warning that the circuit diagram pin numbers may NOT match what is on the vehicle BUT WIRE COLOUR is always correct! So it might be the wire colours from the Pajero/Shogun circuit diagrams could be of use to you but the 2001 4D56 circuit diagram only shows the "Glow ECU" so looks like some significant differences (page 3-160,161).

The 4M4 engine does show an Engine ECU and your statement "The only thing that I can see is different when I turn on the ignition is the check engine light and the heater coil lights do not illuminate" makes some sense and could be a clue. The 4M4 ECU shows the connection from the ignition switch first goes through the GLOW and CHECK ENGINE lamps before arriving at pins 4 and 8 respectively (page 3-150) of the 4M4 ECU (pages 3-148 onwards).

If your 4D56 is similar that would suggest testing the power into and out of the ignition switch, and into and OUT OF the dashboard binnacle that contains those lamps.

https://iam.tj/shogun/Pajero_Gen3_2001_Chapter-03_Electrical_Wiring.pdf

[iam_TJ]

In my last comment when discussing the lack of power at glow and check-engine lamps, which I presume are in some sort of dashboard binnacle, what I implied but did not spell out is that you can, and should, test the lamps themselves AND determine how they are connected in-circuit.

Assuming +Volts from the ignition switch to the lamps in the dashboard binnacle then either:

1. other side of lamp is connected to ground through other components such as a transistor or relay switch within the binnacle (independent of the Engine ECU) and gets its "lamp-extinguish" signal from a third source (e.g. directly from the engine).

2. other side of lamp is connected through other binnacle components such as a transistor or relay switch to ECU's +Volt input and relies on the ECU providing the 'ground' side, which means the +Volt feeds through the lamp to the ECU and the ECU has another terminal connected to ground, and the lamp switch gets its "lamp extinguish" signal from a third source (e.g. directly from the engine).

3. other side of the lamp is connected through other binnacle components such as a transistor or relay switch to ECU's +Volt input and has an additional "lamp extinguish" signal output from the ECU that controls the switch (which would go high (+Volt) to extinguish lamp), and the ECU has separate power and ground inputs (possibly via the same ignition switch input to the binnacle).

4. other side of lamp is directly connected to ECU which provides the "lamp extinguish" signal (an output that would be brought high (+Volt)) so both sides of the lamp see the same voltage (ECU provides switching), and the ECU has separate, independent power and ground inputs (possibly via the same ignition switch input to the binnacle).

5. It's magic!

Hopefully I've made it clear enough since the various permutations have different implications when diagnosing the fault.

[iam_TJ]

And to top it off, one of the implications is that if those lamps are lit when the ECU is disconnected, but extinguished when ECU is connected, is that the ECU is driving its connections to each lamp high (+Volt).

f, with the ECU connected the lamps do not illuminate, and you've confirmed one side of a lamp gets (and has!) +Volt directly from the ignition switch, then the 'other side' of each lamp is getting +Volts as well; whether from ECU or some 3rd source.