jump starting late model vehicles (2007 and up)

[davethewave]

I'm doing roadside service using a 2007 HHR.My question is when doing jump starts isn't it safer
to have my car not running to prevent damage to the ECM (computer)?
This is performed after trying to start the dead battery with A jump box, but fails.

[carriedi]

my recommendation is if you cannot jump a car with a jump box, charge up your jump box.

now, why didn't your jump box work? Was it fully charged up and you ran the box dead from extended cranking? If so, stop cranking so much and find out what you are missing. Spark, the correct fuel pressure, injector pulse, good compression? If your jump box doesn't work on a car is it because it won't turn the engine over fast enough, get a batter jump box with more cranking amps.

I do not recommend you use jumper cables to another vehicle. Too many times I have had customers come in with computers damaged from giving someone a jump. Sometimes they hook the batteries up backwards and blow up stuff and sometimes they hook it up right but (something wrong the the car that doesn't start) spikes something in the donor car and things don't work like they used to. After damage has been done, How many times do the people that asked for help to jump their car paid for the repairs needed on the donor car? None so far in over forty of working on cars so far.

Buy a jump box. Buy a big jump box (big in amps not size) Buy two jump boxes.

if you have room in you car for two batteries in the car, one to run the car and one to jump vehicles and you put in a battery isolator to charge both batteries but diodes in the isolator should keep the spikes from backing up the the main car's systems. But a jump box is preferred. This way, if anything happens, you can always drive home...