FBH The end of the SAGA ?

[kael]

OK that is clear about the connecter sequence.
But what about my other question, about measuring the suspected SMD resistors with the multimeter while the resistors are still soldered? Will that give a proper read out? I suppose you better of by first desoldering it (at least 1 side).

[kael]

In Post nr 192 FrenchMike says:

Sorry Jack, you're not allowed to apply any external 12 volt on pin 1.
Apply 12V on pin 3

In the FAQ:
https://www.the75andztclub.co.uk/forum/showthread.php?t=100297&highlight=fbh
under the section Ready to test I see:

Note - Model 66232C (early) requires +12 volt to pin 1
Whereas Model 98570B (later) requires earth to pin 3

Are we talking about the same thing here?

[Union Wheels]

Hi Kael,
just to make it clear, all models are normally switched on by applying 12 volts to pin 1.

To force start-up on model 98570B connect pin 3 to chassis.

To force start-up on model 66232C connect pin 3 to 12 volt supply.

If you wish to start-up either unit with pin 1, put a diode in series with this new supply.

Hope this clears things up, Pete.

[FrenchMike]

Originally Posted by kael

OK that is clear about the connecter sequence.
But what about my other question, about measuring the suspected SMD resistors with the multimeter while the resistors are still soldered? Will that give a proper read out? I suppose you better of by first desoldering it (at least 1 side).

I can't imagine desoldering them before test ...

[FrenchMike]

Originally Posted by kael

In Post nr 192 FrenchMike says:

In the FAQ:
https://www.the75andztclub.co.uk/forum/showthread.php?t=100297&highlight=fbh
under the section Ready to test I see:

Are we talking about the same thing here?

Sorry,all is said:

you're not allowed to apply any external 12 volt on pin 1.

It's alreary occupied ..and you risk damaging the ECU !!!

If you want to force it,apply 12 volts on pin 3. (66232)

Mike

[HarryM1BYT]

You can avoid the risk of damaging the FBH ECU, by connecting/ disconnecting the two plugs in the wrong order, by cutting the data wire.

It serves no useful function on the 75, other than when connected up to a T4 for diagnostics. On the BMW the data wire allows the FBH to be started by the radio unit, but not the 75.

[kael]

Last year I added a heated seat switch to manually switch on the FBH and 3 months ago I also added GSM control. I also have a LED connected to pin6 so I can see the pulses for the FBH fuel pomp.
That all worked fine until last week when I noticed the FBH didn't fired up anymore.
With manual override my 98570B, I timed the starting sequence;
the fan runs for 2'2" then stops and after 5" it starts again for another 2' then it stops again and nothing more.
I don't hear the pump clicking neither do I see the pulses in the attached 12V led on pin 6.
I checked the PCB and changed the 3 resistors. The 47K showed infinite, the two 4K7's I could measure first but not after changing the 47K... I thought. To make sure I changed all 3.
But still no change.
The glow plug measures about 0.5 Ohm as far as my meter show this correct.
Any ideas for the next steps to try? I'm really missing my FBH on short rides in these cold days now.

[FrenchMike]

The pulsing pump runs when and only when all the Securities are clear

Here is a faulty glowplug timing:



Not easy to measure the glow plug resistor without a millihom meter ...

in case

http://sales.butlertechnik.com/webas...n-kit-9017813b

Mike

[HarryM1BYT]

Originally Posted by kael

The glow plug measures about 0.5 Ohm as far as my meter show this correct.
Any ideas for the next steps to try? I'm really missing my FBH on short rides in these cold days now.

You cannot measure the extremely low resistance with an ordinary meter, the only way without buying special equipment is to measure the current flow at a known voltage and use Ohms Law to calculate it.

Your symptoms suggest your PCB may need the expertise of FrenchMike.

[Union Wheels]

Hi kael,
have a look at the PC board where the glow pin plugs in, and see if there is any sign of a dry joint or high resistance connection on the plug pins. With high current low voltage operation a good joint is essential.

You may also like to check the operation of the electric water pump by feeling for the pulses in the water pipe.

Pete.