Q: Battery connected backwards and won't start

asked by on

The battery in my car was connected backwards. I replaced the blown relays that are in the fuse box. There is full power to all acc, but the car just won’t crank and it won’t turn over. So I jump-started the starter and it’s working, but it’s not getting the signal. Everything else in the car works fine, as far as I can tell. What should I do next to find the solution?

Hello. Most of the time this is caused by a failed main fuse. If the fuses have been replaced then it is more than likely a bad module. In most cases the engine control module will fail when the battery is jumped backwards.

The computer needs to be scanned with a scan tool to see if it is powering up and seeing sensor signals. If you need to have this done, consider YourMechanic, as a certified mechanic can come to your home to diagnose your starting problem. An accurate repair can be made one the problem has been pinpointed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Battery connected backwards and won't start

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car surges when stopped & suddenly dies while driving

Hey there, thanks for writing in about your 2001 Chrysler LHS. Both of these problems can be dangerous and can only be diagnosed by verifying the problems first by a mechanic to diagnose them. A scan for codes may show...

Q: My 1991 geo prizem gear shifter is locked

You should first check to see if the brake lights come on when you press the brakes? If no brake lights then check and replace the brake light switch. If brake lights work then you may have a shift lock...

Q: What could cause blown turn signal fuses if the turn signal switch and the flasher relay have been replaced?

Hello there, a few common faults will cause your turn signal fuse to blow repeatedly on your 2003 Jeep Grand Cherokee. If the blower and turn signal issues started at the same time its very likely there is a short...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...