Start - But no Stop

Over the last year, we have been getting a steady stream of enquiries about how Stop-Start works. Most garages have some idea of the basic principals of some systems, but there are many problems associated with Stop-Start operation across a wide range of vehicle types.
    Two common types we get calls about are the Reversible Alternator systems, fitted to French vehicles, and the more familiar starter motor system fitted with an up-rated starter motor.
    These systems have some very specific requirements to operate correctly. Here are some of the conditions that will disable the Stop-Start system:
1 Poor battery state of charge, and battery overall health: (Stop-Start will wait for battery charge level to come up before operating )
2 Heating or air conditioning requested
3 Seatbelts not fastened
4 Doors not shut
5 Neutral position sensors not working/calibrated
6 Outside temperature sensor not working
7 Age of drive belt on reversible alternator systems requires a diagnostic reset when replacing the poly belt
8 Battery registration of the correct type of battery, normally an AGM
9  Fault in the intelligent battery sensing system
10 PSA Group (Peugeot-Citroen) use a reversible alternator system (combined with a super capacitor and internal sensors to monitor the actual position of the rotor). The capacitor boosts the voltage momentarily to kick the alternator into rotation, but it needs to know the actual position as it has 3 phases and needs to know which one to push the voltage through first. This then rotates the engine via a ribbed belt.
    These systems also use a conventional starter motor for cold starting of the engine, then the Alternator assumes this role when the engine is warmed up. Confusing when you first see this system.
    When servicing these vehicles, care must be taken when working with super capacitors, as they can be dangerous if removed while charged. When replacing parts, such as drive belts, batteries, intelligent battery sensors and manual gearboxes, all these items will need to be programmed before the Stop-Start system will work correctly.
    I hope this helps give some insight into problems garages are encountering. We offer Stop-Start training, and find the technicians are benefitting from these courses, and they are always well attended.
    Join our growing team of members today, who all have access to 1000’s of answers to tech questions on demand. Call us now on 01-905-9500 to join or for more information.