2015 Multistrada 1200S DVT - Fuel pump relay not operating on switch on, WHY ?

lochnagar

lochnagar

Active member
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 .

Questions :-

1. 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).
With the ignition on and the start button depressed this changes to negative / earth which operates the relay to fire up the pump.

2. 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.
 

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Without diagnostics, gonna be difficult to remedy, one of the more electronically mined will along shortly for sure.
A wee bit more history prior to the problem, your bike? client bike?
Does the bike run now?
Does the EML light up?
The 286.4.257.1C relates to testastretta engines, but the 286.4.258.1A relates to testastretta dvt, ECU revision 1E now.
Is the cat still fitted? I note it has an aftermarket pipe fitted, perhaps the mutt was fitted with a mapped 2571C for the decat and pipe?
Is there a fuel pressure sensor? Have you tried purging the fuel line to see if the fuel pump operates on ignition to pressure the line?
 
Change the fuel pump relay first.
Pin 56A on the ECU puts out the voltage to the fuel pump relay, as you say pin 38A is the circuit continuity earth.

I can’t see how an ECU can become corrupted due to a power disconnection.

AFAIK the ECU is programmed to provide power to the fuel pump relay at key on but there’s an override in as much as if there’s no crank rotation within X secs it cuts the power (breaks the earth inside the ECU). As soon as the the ECU recognises crank rotation it re-establishes the circuit to the fuel pump relay.

The sub 5v you recorded for a while after key off is because the ECU has a power down phase, it doesn’t go to sleep immediately at key off. Thus, it’s still feeding power into pump relay pin 1 which is coming out of pin 2, if you measured voltage between 2 and an earth, say the frame, engine casing or battery -ve you’ll still see volts for a while.
 
BobTheBounder said:
Without diagnostics, gonna be difficult to remedy, one of the more electronically mined will along shortly for sure.
A wee bit more history prior to the problem, your bike? client bike?
Does the bike run now?
Does the EML light up?
The 286.4.257.1C relates to testastretta engines, but the 286.4.258.1A relates to testastretta dvt, ECU revision 1E now.
Is the cat still fitted? I note it has an aftermarket pipe fitted, perhaps the mutt was fitted with a mapped 2571C for the decat and pipe?
Is there a fuel pressure sensor? Have you tried purging the fuel line to see if the fuel pump operates on ignition to pressure the line?
Click to expand...
Aye Bob, The bike does run for a brief period as the fuel pump operates when the starter button is depressed but stops on release as the pump ceases to function and the fuel rail pressure drops.
The cat. was removed by whoever fitted that "silencer" which I suspect is the reason for the ECU change to the .257.1C to compensate for the change.
The fuel pressure sensor is part of the fuel pump / filter assembly as it's a single feed system rather than the usual out / return of the 851 - 916 - 886 - 998 models with the external pressure sensor.
The problem is the ECU does not provide the -ve. earth on pin 38A to operate the pump relay on the initial power up but does with the starter button depressed.
 
West Cork Paul said:
Change the fuel pump relay first.
Pin 56A on the ECU puts out the voltage to the fuel pump relay, as you say pin 38A is the circuit continuity earth.

I can’t see how an ECU can become corrupted due to a power disconnection.

AFAIK the ECU is programmed to provide power to the fuel pump relay at key on but there’s an override in as much as if there’s no crank rotation within X secs it cuts the power (breaks the earth inside the ECU). As soon as the the ECU recognises crank rotation it re-establishes the circuit to the fuel pump relay.

The sub 5v you recorded for a while after key off is because the ECU has a power down phase, it doesn’t go to sleep immediately at key off. Thus, it’s still feeding power into pump relay pin 1 which is coming out of pin 2, if you measured voltage between 2 and an earth, say the frame, engine casing or battery -ve you’ll still see volts for a while.
Click to expand...
Aye Paul, The fuel pump relay (46 on diagram) is fully functioning. On power up the Main relay (45 on diagram) operates and applies +12v to one side of the pump relay coil and pins 55 / 56A of the ECU as well as to other assemblies. This should trigger the ECU to apply an earth to pin 38A to operate the pump relay but the damn ECU doesn't, hence my dilemma.
Question :- Does the ECU require some other input as well as the +12 on 55/56 to return the earth on 38 ?
I understand the latent + 3.5v. measured on 38 for the short period as the ECU capacitors gradually discharge to provide a controlled, rather than immediate, power down.
The bike came to me as a fully functioning machine and its current state is doing my heid in !!!!
Only work I've done is set the valve clearances, changed the belts and repaired the fuel outlet pipe retaining ring on the tank assembly, nothing really life threatening .
 
lochnagar said:
Aye Paul, The fuel pump relay (46 on diagram) is fully functioning. On power up the Main relay (45 on diagram) operates and applies +12v to one side of the pump relay coil and pins 55 / 56A of the ECU as well as to other assemblies. This should trigger the ECU to apply an earth to pin 38A to operate the pump relay but the damn ECU doesn't, hence my dilemma.
Question :- Does the ECU require some other input as well as the +12 on 55/56 to return the earth on 38 ?
I understand the latent + 3.5v. measured on 38 for the short period as the ECU capacitors gradually discharge to provide a controlled, rather than immediate, power down.
The bike came to me as a fully functioning machine and its current state is doing my heid in !!!!
Only work I've done is set the valve clearances, changed the belts and repaired the fuel outlet pipe retaining ring on the tank assembly, nothing really life threatening .
Click to expand...
I’ll have to look into it further but as I’m on the road all day today I’ll not get chance to do so until tomorrow.

On the face of it I can’t see why pressing the start button causes the fuel pump relay to operate, they’re different circuits (albeit the ECU is seeing what’s happening).
 
Dox said:
I was going to answer, but I see someone has already said what I was going to... 👀




🤣
Click to expand...
Say it anyway Dox as you may have a slightly different slant on it.
Ony port in a storm as the saying goes and all I see are fast passing straws.
 
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You asked which bike uses the 28642571C ECU = 2015 Multistrada 1200S
Have you checked the BBS unit? Part number may be 38510432F
 
chrisw said:
You asked which bike uses the 28642571C ECU = 2015 Multistrada 1200S
Have you checked the BBS unit? Part number may be 38510432F
Click to expand...
Aye Chris,
As far as I can glean from the workshop manual for the 2015 1200S + ABS + DVT the BBS has no bearing in the operation of the fuel pump, BBS parameters listed below as copied from the manual :-

In Signals:-
Front wheel accelerometer;- Bottom yoke accelerometer (if enabled);- Level sensor;- Preload position (if enabled);- Shock absorber position sensor (if enabled);- EXVL valve position- Rear stop light.

OUT Signals:-
Front suspension damping (if enabled);- Rear suspension damping (if enabled);- EXVL valve actuator;- Preload actuator (if enabled);- Tail light;- Rear LH turn indicator;- Rear RH turn indicator

The ECU relevant to this model is 285.4.258.1A, information from JHP - Ducati Coventry and checked with frame and engine number, they have no listing of the 286.4.257.1C as fitted to this bike and I suspect the ECU was changed to correct the fuelling following the removal of the exhaust valve and the fitting of a non silencing "silencer".
 
Dear All,
Anyone out there with a 2015 to 2017 MS 1200S please try the following and let me know the result :-
1. Side stand down, switch on ignition and check if the fuel pump operates, Yes or No ?
2. Side stand up, switch on the ignition and check if the fuel pump operates, Yes or No ?

Idea is to ascertain if the side stand switch is a safety parameter to disable pump operation if stand down and requires it to be in the up position for the pump to operate.

Thanking you all in anticipation of your replies.
 
I’ve had a couple of Multis of that vintage, but don’t have one now.

My previous gen Supersport (939) had a known issue when cornering hard, the side stand would move and cut the engine. Very disconcerting when getting a move on.

Not the answer to your question, but might be linked?
 
lochnagar said:
Dear All,
Anyone out there with a 2015 to 2017 MS 1200S please try the following and let me know the result :-
1. Side stand down, switch on ignition and check if the fuel pump operates, Yes or No ?
2. Side stand up, switch on the ignition and check if the fuel pump operates, Yes or No ?

Idea is to ascertain if the side stand switch is a safety parameter to disable pump operation if stand down and requires it to be in the up position for the pump to operate.

Thanking you all in anticipation of your replies.
Click to expand...
When I had my 2017, the answer to both is yes, the pump would prime.
 
BobTheBounder said:
When I had my 2017, the answer to both is yes, the pump would prime.
Click to expand...
Well Bob that then leads to another question.
The side stand 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 you state the fuel pump still operates, if you press the starter button did the engine start ?
If it does then what the F--- does that side stand switch do for safety ?
 
Ok bud, scenario uno, bike on the main stand, side stand up, ignition on, she's in neutral, pump primes hit starter she starts.
Scenario due, all of above apart from she is in gear, prime but no start until clutch engaged then starts.
Scenario tre, as one but on side stand at the beginning, primes and starts.
Senario quattro, as two prime no start until clutch engaged then start.
So to expedite what the side stand switch does for safety. The ECU tells the bike that the idiot on board is trying to pull away with the side stand down!
I had an issue with the switch on my gen one mutley, only happened twice after riding in torrential rain, where the she cut out and would restart, until gear engaged and she cut straight out. I shorted the switch, the ECU thought the stand was down.
 
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