fournguy Posted February 18, 2019 Report Share Posted February 18, 2019 Recently my 2016 Cmax H had the 12 V battery replaced because it would not start. The same thing is happening again! No lights no Power to dash nothing, no sign of life when the push to start is used.... The first shop told me to tow it else where after giving me no idea what was wrong Is it likely the 12V battery again as i mentioned it CAN NOT BE jumped at all ,.. it Can't be jumped started but jumping does makes the internal lights and dash lights turn on when connected to another car... there are about 3 weeks in between the first time the car died and this new event The last shop charged me 600$ to diagnose and replace a dead 12 V .... Hoping someone has an idea of whats wrong or can give me some trouble shooting ideas. I paid cash for this car about a year and a half ago this has me so worried should I sell the car back to the dealership and take the loss Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted February 18, 2019 Report Share Posted February 18, 2019 Are the “shops” you mentioned Ford dealerships? If the lights come on when jumped, the CAN and BodyCM should be OK. Did the shops scan all modules for diagnostic trouble codes especially the BECM and DC/DC converter? If there are issues with connecting to the HVB or DC//DC converter has issues, the car won’t start. Have you measured the 12 V battery voltage under hood? Before trying to jump and when jump starting. If DC/DC converter is operating, the voltage should be higher when trying to start (key on). Do the lights stay on if you remove the jump start battery? Quote Link to comment Share on other sites More sharing options...
fournguy Posted February 18, 2019 Author Report Share Posted February 18, 2019 *** Update ****Went to the dealership and bought a brand new battery again ..... and ... nothing happened ... Car is still dead with a new battery, no signs of life.... Finally broke down and had it towed once again to a dealership at my expense... I am starting to hate this car it seems like a lemon I feel like cutting my losses and running .. Any thoughts now that its known the 12V batter being brand new didn't touch the problem? Quote Link to comment Share on other sites More sharing options...
ptjones Posted February 18, 2019 Report Share Posted February 18, 2019 (edited) What does the dealership say? Maybe the 12v batt. isn't making good contact at one of the cables. :headscratch: Paul Edited February 18, 2019 by ptjones Quote Link to comment Share on other sites More sharing options...
homestead Posted February 18, 2019 Report Share Posted February 18, 2019 (edited) Read Plus 3 Golfer post again, that is most likely way to proceed. (HVB or DC//DC converter) Edited February 18, 2019 by homestead Quote Link to comment Share on other sites More sharing options...
joe Posted February 21, 2019 Report Share Posted February 21, 2019 Over the past 2 years, I've had battery problems with the 12v battery. So, I bought one of those lithium battery startup devices from Costco to jump my C-Max. Attach leads to connectors under the hood and the electronics came alive and I was able to start the engine. This saved having to have the car towed to the dealer.Since I bought my 12v batteries from Ford, they have replaced that last two defective batteries for free. ptjones 1 Quote Link to comment Share on other sites More sharing options...
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