Dear All,
I have a 2015 Multistrada 1200S DVT on the bench with a fault in which the fuel pump relay does not operate on power up but does operate with the starter button pressed.
The fuel pump relay should power the pump on switch on to pressurise the fuel rail but the correct signal (negative / earth) from pin 38 of ECU-A is not being returned to operate the pump relay.
A Motronic 286.4.257.1C Engine Control Unit is fitted which Ducati Coventry (JHP) have no record of, the standard ECU for this bike is 286.4.258.1A .
Only work I’ve done is set the valve clearances, changed the belts and fuel filter and repaired the fuel outlet pipe retaining lock ring on the tank assembly, nothing really life threatening.
Questions :-
- On ignition switch on what device informs the ECU to apply a Negative / Earth to pin 38A to operate the pump relay ?
(Note that with ignition off a 3.4 + volts is present on pump relay pin 2 coming from ECU pin 38A which drops to no condition after a time out period of around 2 minutes, I understand the latent + 3.5v. measured on 38 for the short period is the ECU capacitors gradually discharging to provide a controlled, rather than immediate, power down ).
With the ignition on and the start button depressed this changes to negative / earth which operates the relay to fire up the pump.
- What Ducati model uses the Motronic 286.4.257.1C ECU ?
Prior to working on any bike I always run the engine and check all functions correctly before disconnecting the battery and commencing work, and all was well at that time but not anymore. Is it possible to corrupt the data within the ECU with a long power outage ? I doubt this very much.
I’ll await your responses before splashing out on a replacement 286.4.257.1C ECU.
Thanking you in anticipation of your replies.
Question 1 - I used Google Gemini and typed in your question and got this output: Useful info on the side stand switch, kill switch safety feature too - see below.
Understanding the specific triggers for an ECU to activate the fuel pump relay involves delving into the intricate workings of the motorcycle’s electronic control system. Here’s a breakdown of the key elements involved:
- Ignition Switch:
- The initial trigger is, of course, the ignition switch. When turned on, it signals the ECU to begin its startup sequence.
- ECU Logic:
- The ECU (Motronic 286.4.257.1C in your case) is the central processing unit. It receives signals from various sensors and then executes programmed logic.
- Upon receiving the ignition-on signal, the ECU checks various parameters. Crucially, it’s programmed to activate the fuel pump relay to pressurize the fuel system.
- Safety Checks:
- Modern ECUs incorporate safety checks. Before fully engaging the fuel pump, the ECU may verify:
- Engine kill switch position.
- Side-stand position.
- Other relevant sensor data.
- These checks are in place to prevent the fuel pump from operating in unsafe conditions.
- Timing:
- The ECU typically activates the fuel pump for a short duration when the ignition is first switched on. This primes the fuel system.
- Once the engine starts, the ECU continues to control the fuel pump operation.
In essence, the ignition switch initiates the process, and the ECU, based on its programming and sensor inputs, determines when and how long to activate the fuel pump relay.
When looking at the pin 38A, this is the output from the ECU that when the ECU grounds this pin, it energizes the fuel pump relay.
To find very specific ECU pinout information it is best to consult the factory service manuals for your specific Ducati model. These manuals will contain very detailed wiring diagrams.
Sources and related content
ECUs Explained - APAGCoSyst.
Question 2 - again with Google Gemini and typed in your question and got this output:
Based on the information available, the Motronic 286.4.257.1C ECU is used in a range of Ducati models. Specifically, it’s been associated with:
- Ducati Multistrada 1200
- Ducati Diavel/X-Diavel
- Ducati Panigale 899/1199
- Ducati Hypermotard 939/SP
- Ducati Hyperstrada 939
- Ducati Monster 1200 R
It’s important to note that ECU variations can exist within model ranges and years. Therefore, when dealing with specific ECU information, always verify with reliable Ducati resources or authorized dealers.
I also got this ECU replacement link if it helps
Aye Steve, many thanks for the reply and that side stand switch is a wee bit of a conundrum.
The switch is a 3 wire affair, pin 3 is to earth, 1 to 6A of the ECU and 2 to 36B of the ECU. With the stand down pins 1 & 3 are looped to put an earth to ECU 6A, side stand up the earth is removed and pins 1 & 2 are looped effectively short circuiting ECU pins 6A & 36B.
Question :- with the side stand down another MS 1200S owner stated that the fuel pump still operates, however if the starter button is depressed does the engine start ?
If it does then what the F— does that side stand switch do for safety ?