smart charge system

[dye29]

hy all im trying to diagnose a problem the alternator wires theres 3 im wundering what each one of these are can anyone help

[Altransit]

On which van

[dye29]

sorry its a transit connect t200

[Altransit]

If you look in the Connect section, there's a sticky at the top

[dye29]

cant find her

[tom-moby]

First, check the battery, not just condition, but correct type. A lead acid battery will not work properly with smart charge, it must be Silver Calcium. Easy to over look.

Next, put a meter across the battery. Remember when you remove the smart charge 3 pin plug from the back of the alternator, it reverts to a conventional alternator. If you do not have about 13.8 volts, carry out basic charging system checks and suspect the alternator, its not a smart charge fault.

Correct the charge voltage from the alternator, then its time to start on the smart charge system, and you will need a scope. First the system:

Pin 1 = Alternator Feedback

Pin 2 = Alternator Load Request

Pin 3 = Reference Voltage

Pin 3 must MATCH battery voltage. Its fed from a fuse in the CJB, and a high resistance on the fuse contacts causes a volt drop, and the smart charge drops out.

Next pin 1 & 2 need checking back to the PCM for resistance, isolation from ground, and each other. If ok, its out with the scope.

Pin 2 is the request from the PCM to the alternator. This will be a square wave pattern that will change with load request. So lights, screens etc on and monitor for a change in the pattern. (Obviously back probing with the plug connected)

No change in the scope pattern means no request from the PCM, you should now suspect a PCM fault. Correct pattern and move on.

Pin 1 is the feedback from the alternator and MUST remain a constant square wave pattern. If this pattern mirrors the one on pin 2, the smart charge part of the alternator is faulty, and a new unit is required.

With these simple checks, you should always be able to diagnose a smart charge fault.

Another point to add is, never, ever, jump start a Smart Charge vehicle with a flat battery.

The system can produce up to 18 volts, which can fry major modules.

The theory behind smart charge, is a battery will take a charge at its most efficient when it’s cold. Following start up, the PCM checks the Engine coolant temp, and intake air temp, and calculates a cold engine. It will then boost the battery charge, pulling it back as it calculates the under bonnet temp coming up. Its not there to compensate high demand as is the common misunderstanding.

The problem comes on a jump start, when the PCM sees a cold engine, and then a poor battery condition, and can then instantly zap out about 18 volts because its trying to recover the battery. This sudden surge can cook modules.

[Mrspot]

good post and its interesting to know exactly what each of the three wires does (I'm currently having the same problem, red wire is dead, alternator about to be replaced)...however....not sure your average Joe has a scope

[dye29]

can anyone answer me with this its a new alternator and charging battery at 14.2v when engine running oh and its a new silver calcium bosch battery ,the smart charge system is ok now as ive fixed the wires but when i leeve on my drive overnight i go to fire it up and its dead

[tom-moby]

good post and its interesting to know exactly what each of the three wires does (I'm currently having the same problem, red wire is dead, alternator about to be replaced)...however....not sure your average Joe has a scope

True but scopes are getting so cheap nowadays that it won't be long before everyone has one. I think I saw a little digital thing in Maplins for about £70, very good spec. I think you can buy a programme to turn an I-phone into a scope, not sure about that, don't follow phone technology.

Rapid sell the UNI-T81B for around £250, can buy it direct from China for £120, very nice little tool, full mult-meter and scope in one, does the job, very useful and affordable alternative to a basic meter. I'd recommend it, I have one, great liitle thing, don't worry too much about it value wise either. Useful for all Transit/Connect owners for easily managable DIY fault finding on smart-charge/fuel-pressure sensor/return solonoid/wheel sensors and piles of other stuff.

Have a look round see whats available, equally usful on all vehicles, particularly newer models