Resetting fault codes on the ECU

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Tony x
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Resetting fault codes on the ECU

Post by Tony x » Tue Sep 05, 2017 9:14 am

Hi. I gather you can reset the ECU by removing two fuses. Can anyone tell me which?
Currently I have to disconnect the batteries which is a hassle as it means retuning the radio and altering the alarm settings.
I ask as sometimes when I switch on the scavenger fan ( via a switch that puts a 400 ohm resistor in parallel with the temperature sensor ) it will register a fault - the glow plug light will flash.
The Bongo is a new shape, X reg 2.5 diesel
Cheers all.
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Re: Resetting fault codes on the ECU

Post by rita » Wed Sep 06, 2017 12:16 pm

Tony x wrote:Hi. I gather you can reset the ECU by removing two fuses. Can anyone tell me which?
Currently I have to disconnect the batteries which is a hassle as it means retuning the radio and altering the alarm settings.
I ask as sometimes when I switch on the scavenger fan ( via a switch that puts a 400 ohm resistor in parallel with the temperature sensor ) it will register a fault - the glow plug light will flash.
The Bongo is a new shape, X reg 2.5 diesel
Cheers all.

Why do you need to manually switch on the Scavenger Fan,I would have thought it would go against the ECU/EMS principal?

If you need to kill the ECU/EMS I would imagine its the Engine Management fuse/s that you need to remove. [-o<

Good Luck.
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Re: Resetting fault codes on the ECU

Post by the1andonly » Wed Sep 06, 2017 11:48 pm

Tony
fuse 1 is one of those that power the ECU. Maybe the only one?
If it blows the engine problem light (coil) comes on (flashing? cant remember) indicating an engine problem
It covers a shed load of other devices inc radio. In my mind a poor choice to move to the LB( fry the LB no start van). Rewire the radio, add LB powered lighting. Its important to be able to run a camp site/situation with both LB and SB just in case one is fried. not even proper dual redundancy.
I also understand the "need" for a scav fan overide switch.
when it really needs to be used i'm still on the learning curve.
Still monitoring temperatures in 2 engine positions and bottom of rad in a number of situations on mine (including pissing about putting the drive away awning on).
Now added the same monitoring to a Bongo with no head problems but leaking and no stat (subtle sensor positions to be adjusted as I had difficulty believing the results.
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Tony x
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Re: Resetting fault codes on the ECU

Post by Tony x » Thu Sep 07, 2017 10:38 pm

Hi and thanks very much for the replies.
One reason I have the scavenger fan overide switch is for when I park up for a few minutes when the engine is hot. The engine temperature will rise about 10 degrees and can come close to triggering the engine temperature alarm when the ignition is turned back on. I guess the scavenger also helps prevent hot spots in such a situation.
For info - if the ignition is off and I turn the scavenger fan switch on, the fan runs for a few minutes and then turns itself off. This is ideal for when parking.
Regarding resetting the ECU I understand it has a main power supply and a backup. It's the fuse for the backup I need to track down.
If I find it I'll post where it is.

Powering the ECU from the leisure battery and the problems this can cause is a good point.
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Re: Resetting fault codes on the ECU

Post by Tony x » Thu Sep 07, 2017 11:02 pm

Hi. Having just looked through the masses of information I've gathered from owning two Bongos I think it may be fuse 9 in the cabin and fuse 9 again under the bonnet. I've yet to check this but , if correct, applies to diesels up to September 2001
The glow plug light doesn't always flash when I use the scavenger overide but, next time it does I'll try to reset it by removing the number 9 fuses and add to this thread.
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Re: Resetting fault codes on the ECU

Post by g8dhe » Fri Sep 08, 2017 9:51 am

The fuses for the ECU are well documented, top left 10Amp is the back up fuse, and far left second row is the main supply.
However, its not the wisest way of avoiding the problem your causing by using a fault condition to trigger the scavenger fan, as of course your loosing all the other engine settings that the ECU has probably stored about the running of the engine, no one has actually reverse engineered the software but there would be no need to have a backup supply if there were no stored variables about the engine ......
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Re: Resetting fault codes on the ECU

Post by rita » Fri Sep 08, 2017 9:32 pm

g8dhe wrote:The fuses for the ECU are well documented, top left 10Amp is the back up fuse, and far left second row is the main supply.
However, its not the wisest way of avoiding the problem your causing by using a fault condition to trigger the scavenger fan, as of course your loosing all the other engine settings that the ECU has probably stored about the running of the engine, no one has actually reverse engineered the software but there would be no need to have a backup supply if there were no stored variables about the engine ......

=D> =D> =D>


Good Luck.
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Tony x
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Re: Resetting fault codes on the ECU

Post by Tony x » Fri Sep 08, 2017 11:59 pm

Cheers again for the replies.
Although I now know how to reset the ECU the advice is not to do it. I'm a little unsure now as I have little knowledge of the data the ECU stores and the impact of losing it.
I guess one possible answer would be to add a few more ohms onto the resistor that I switch in parallel with the temperature sensitive resistor that triggers the scavenger. This might bring the overall resistance into the window the ECU 'sees' as OK and not a fault.
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Re: Resetting fault codes on the ECU

Post by Tony x » Sat Sep 09, 2017 6:11 pm

Hi,
as a quick update I measured the resistance of the, err...resistance I switch to be in parallel with the scavenger fans temperature sensitive resistor. It was only 150 ohm or there abouts - a lot less than the 400 ohm I thought it was.
It is now 504 ohm which works just fine although I tried it with a relatively cool engine.
Incidentally, 551 ohm was too much - the fan wouldn't turn on.
If there's problems with it working when the engine is properly hot then I'll post again. I think it will be ok though as the fault light would only come on with the switch when the engine was particularly hot - about 5 or 6 deg above the temperature the thermostat in the cooling system opens and allows coolant through the main radiator or, to describe it another way, a few degrees under the point where the two main radiator fans kick in.
The Bongo has no cooling issues I'll add,
Tony
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Re: Resetting fault codes on the ECU

Post by cmm303 » Sat Sep 09, 2017 6:29 pm

the1andonly wrote:Tony
fuse 1 is one of those that power the ECU. Maybe the only one?
If it blows the engine problem light (coil) comes on (flashing? cant remember) indicating an engine problem
It covers a shed load of other devices inc radio. In my mind a poor choice to move to the LB( fry the LB no start van). Rewire the radio, add LB powered lighting. Its important to be able to run a camp site/situation with both LB and SB just in case one is fried. not even proper dual redundancy.
I also understand the "need" for a scav fan overide switch.
when it really needs to be used i'm still on the learning curve.
Still monitoring temperatures in 2 engine positions and bottom of rad in a number of situations on mine (including pissing about putting the drive away awning on).
Now added the same monitoring to a Bongo with no head problems but leaking and no stat (subtle sensor positions to be adjusted as I had difficulty believing the results.
I have fuse 1 moved over to the LB and can start the engine fine with the LB disconnected. Granted I have never tried travelling like that but not noticed a problem when doing maintenance.
Chris with BertieB
'96 White unconverted AFT 2.5L Diesel 4WD
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Re: Resetting fault codes on the ECU

Post by g8dhe » Sat Sep 09, 2017 7:49 pm

As soon as you turn on the Ignition then power is supplied via the switched ignition route and the ECU is quite happy, however it only has RAM - which needs power to retain its memory contents, so switch off and disconnect the backup source and its settings that it learns during running are lost. These values will be regained as the engine goes thru its paces after the start, but until then it will be working on default values only. Just what effect this has on the engine and performance I have no idea, modern ECU's retain the settings in Flash memory which doesn't need power, much the same as smartphones/tablets etc.
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