2001 hyundai elantra gls, we were driving, car died, now wont crank. new batt, cables look good with new ends, nothing, just a click, have power to all accessories and lights. hooked up ODBII scanner, cannot connect to ecm, please help, thanks

 

Do you have a meter to check the voltage across the battery terminals? If the alternator has gone bad, the ignition would run off the battery until the battery voltage was too low. Some accessories would still run, but head lamps certainly would not be very bright. I would also check the fuses in the box under the hood.

 

so we took the new battery back to get tested, tested ok, put new ends on the cables, checked the motor to body ground connection, looks brand new with no corrosion. checked all fuses, voltage across battery terminals is 12.5. still nothing. turn key on, dash lights come on, all accessories work (fan, etc.), headlights work (normal brightness), turn key to start, nothing, just a click. retried to hook up ODBII scanner which has its own battery power to datalink connector under steering wheel, choose option on scanner to read codes, scanner says "must be connected to proceed", but it already is. stumped. is there any way to use a voltmeter on the datalink connector to see if the ecm is outputting to it?

 

The key has to be in the on position for the scanner to work (at least it does with mine). I initially suspected a bad starter solanoid, but a weak or bad solanoid is not going to disrupt a running engine. You may have a bad ECM, or a bad ground wire on the ECM. Wiring schematics for the car are available at http://www.hmaservice.com/.

 

Ken99- thanks for all the input. Our car too is suppose to be in the "on" position as well, but for some reason the OBDII is not detecting a connection to my car. We did try the hmaservice to see what we could find out, but nothing really helped us there either. We are just going to start with the ECM and see where it goes from there. We have tried everything else possible. If this does not work, we will tow it into Hyundai and see if they can help us more. We really appreciate you helpful advice tho, as it helped us to try and narrow it down.