Perplexing electricity
 

Hello from Preston,
I am perplexed at the Raptor. She has had a new battery (spiffy Bosch job) and a refurbished alternator. When I have the aircon on, I press the accelerator pedal and the fan speeds up. When the aircon is on and I indicate left or right, the bulb warning lamp lights up.
Please can anyone help?
As always, any advice welcomed,
All the best,
Dale

Hello Dale,

Regarding the heater blower speeding up, activate the instrument pack diagnostics and select test 9.0. This will display the alternator charging voltage. What does it read at idle and when you press the accelerator?
Do you mean the bulb failure warning lamp? Are you saying that when the air conditioning isn't active, this warning lamp doesn't illuminate?

Simon

Hello Simon,

First, thank you for your advice, I will run the test you mention. Secondly, yes, when the aircon is on and I indicate left or right, the bulb failure warning light comes on. When I cancel the indicator or turn off the aircon, the bulb failure warning light turns off.

Hi Dale,

Thanks for confirming. Whilst the involvement of the air con. might mean a k-bus problem, the first thing I would do is check visually the indicator lenses to see if there is, in fact, a blown bulb. Or have you done that already? :}

Simon

Yes, I checked the indicators. They're all working, but way too fast! Ah, the joys of elderly car ownership ��

Generally when the indicators flash fast, it's due to a dodgy bulb, regardless of the age of a car. The system does activate when there is a poor connection too.

I checked the voltage via the ipk. It says 12.4. Despite googling it, I still don't know if that's bad or not ��

Have this problem with my Transit on left turn, sometimes correct rate of flash, sometimes very fast rate. I think it's a dodgy earth, because I just changed the bulb but possibly didn't clean the contacts enough:duh:

My experience of car electrics is that when you have strange effects, you might have TWO faults that, individually do not have any symptoms, but together, bring up strange symptoms.

Fault 1:
If you have a (marginal) fault, such as a poor connection in the wiring or the bulb holders, of the indicators, you may or may not get a faulty bulb reported.

Because the fault is marginal, a second fault may consistently result in the indicators being reported as faulty.

Fault 2:
If you are getting a reported battery voltage of 12.4 volts while the engine is RUNNING, then you definitely have a charging fault.

The only indication of this fault may be an audible speed change by the fan motor, whenever throttle is applied, and shortly afterwards a dead battery, due to lack of proper charging. So the battery gets changed.

And a reasonable diagnosis would be a faulty alternator, so the alternator is also replaced. As you have done.

So what is the charging fault ?

1) The charging fault may be caused by a poor connection in either the battery or the alternator charging circuit. You cannot assume that because the wires are thick, that there is a good connection.
Faults in the ground connection are often overlooked, and cause difficult to diagnose faults, so the alternator is blamed, and swapped.

2) But if the rubber in the flywheel pulley had perished (and they are all 16+ years old), when the AC is turned on, the (significantly) extra load causes the flywheel pulley to start slipping very SLIGHTLY.

The slipping flywheel pulley leads to a charging fault by the alternator, (but not enough to bring up the alternator warning light). And the subsequent drop in battery voltage causes the marginal indicators to become consistently reported faulty.

Look at the alternator pulley for a (potentially slight) reduction in speed, while a second person switches the AC on/off.

The slowing alternator pulley was initially difficult to see, but as the problem gets worse, a PAS fault may also appear.

And clean up ALL the connections on the indicators. The front ones are very exposed to rain and spray and the rubber seals are probably perished due to age.

:wot: :iagree:

Dale, please confirm that you remembered to have the engine running during the test. I also recommended that you note the voltage both at idle and with the accelerator pressed. Which of those two gave 12.4 volts?

Simon