# Azure Dynamics Transit - Low Voltage Sag



## eelley (Feb 26, 2018)

Hello all,

Hoping for some global wisdom once again. My AZD Transit Connect has been running well since last posting quite sometime ago. 

Lately I occasionally receive the following DTCs when starting the vehicle: 

From the VCU:

P1A20 Battery Control Module "A" Fault
P1A27 Battery Control Module "B" Fault

From either ESS Pack:

P0ADC Hybrid/Electric Battery Positive Contactor Control Circuit High 


These codes, and the accompanying wrench on the cluster, only occur when the key is turned to the start position AND low voltage bus happens to be sitting at 11.6V. Once the DC-to-DC converter kicks in a few milliseconds later, the bus voltage climbs to 13.9V. 

Then the van...drives as normal. 


I have replaced the positive and negative battery/DC-DC converter cables since I was getting voltage drops of .25V to 1V across the ends of each cable under load because of corrosion buildup (like the wire inside the crimp terminals at the DC-to-DC converter were green). Since replacing the cables the headlights no longer dim when turning the steering wheel. 

I replaced the low voltage battery.

I also cleaned the positive and negative terminals and pads on the DC-to-DC converter as well since they looked like they were fished out of a lake. (I wonder why AZD never fitted these vans with a lower splash guard)

I check the technical service bulletins and found that the power steering pump (EHPAS) connector could become corroded and create leakage, but no corrosion was found. 

So, before I start the vehicle I always measure the low voltage supply at the cigarette lighter/12V outlet before starting and sometimes I find it sitting below 12VDC but most of the time, it is above 12VDC. In fact, I just measured the low voltage bus six hours after charging the vehicle to 100% SOC and it measured 12.3VDC. 

So what do you think? Has anyone seen this?

Thanks for any info. 

Eric


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