Car has received a new alternator and battery within the last 4 months. The check engine light came on as well as the check battery like, but after cleaning the IAC valve, the check engine light went off. However, the battery light continued to come on intermittently; could this be caused by the fuel pump? Currently, the car cranks but does not start, and will not take a jump.
Can check battery light be caused by a clogged fuel filter or failing fuel pump? on 2002 Ford Focus
by LMCc in Dallas, TX on December 08, 2011
2 answers 2 comments
ANSWER by patrick mannion , December 09, 2011
Check the fuses and fuse links in case one of these is blown.If the battery light was coming on the alternator was not charging properly. Turn on the ignition switch to the on but not run position. Do you see an icon on the instrument panel representing a battery, if you do not see this battery icon the alternator was not seeing power to allow it to charge. After you do get the engine started, run the engine does the battery icon go out. Put a volt meter across the battery terminals with the engine off, at rest the battery voltage should be 12.6 volts if the battery is fully charged. Now get a friend to start the car while you watch the voltmeter, the voltage reading across the battery should read approximately 14.6 volts if the alternator is charging correctly. It's best also to properly test the alternator by using an oscilloscope to look at the alternator diode patter. To address the no start condition ,see if you have fuel and spark going to the engine.Check for fuel pressure (you will need a fuel pressure gauge and look up the specified fuel pressure for your vehicle). Remove the fuel hose that goes to the fuel rail and get a friend to crank over the engine to see you have adequate fuel volume (you should have approximately 1 pint of gasoline in ten seconds of cranking). Off course take proper precautions as gasoline is highly flamable. Next "listen" to the fuel injector. Using a mechanic's stethoscope (or use a long screw driver placing the handle end up to your ear place the metal tip end of the screwdriver against the body of the fuel injector), get a friend to crank over the engine while you "listen" to the fuel injector listen to each injector at the same point of the injector body. You should hear "click, click, click" as the injector is electrically opened and closed by the computer. If the injector is not being triggered you will not have fuel getting into the engine's cylinders. Disconnect the electrical connector at the fuel injector with the ignition key in the "on" position, (next position after the accessory position) you should have 12 volts at one of the two wires at the injector. This true for most vehicles but you need to consult a workshop manual for your vehicle to see that this is true for your vehicle. When the engine is running the second wire at the injector gets (triggered) grounded by the computer in your vehicle many times a second controlling exactly when and how much fuel gets injected into the engine. To check for spark you need to check for spark at the spark plug/end of the ignition coil but this is over 20,000 volts and you stand the risk of shock if you don't know what your doing. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online
COMMENT by alTester01 , July 07, 2013
I have a similar problem. The check battery light comes on intermittently while driving. The voltage of the battery at rest is around 12.4, and during charge is approximately 14.6 dropping to around 12.7 when the cooling fans kick on and the engine is at slow idle, but when idling up goes back up. I connected a o-scope and it appears all three phases are outputting properly. However I also noticed that while idleing with brights on with teh engine idling at around 450 RPM the voltage seems to modulate going up and down a bit, but if I idle above around 800 to 1000 RPM then voltage is solid with the normal charge ripples. However while driving down the road at around 1750 RPM the Battery light will come on for a minute or so then go out. Other than that it seems normal. It is warm (80' outside) when this occurs. It occurs with the AC on or off. With the headlights on or off. We also have a rough idle condition that I suspect is a IAC valve that I have not yet addressed. Any ideas?
ANSWER by mastertech6371 , December 08, 2011
no. it is a charging system issue. the check engine light could be anyone of over 1500 codes. Roy
COMMENT by LMCc , December 09, 2011
Roy, Thanks for the reply, but I wondering what could cause the check battery light if the alternator and battery are new. Also I took the car back to the shop and their check showed the alternator was charging at 14 volts. I know that the check engine was due to a dirty IAC valve, which I had cleaned. and it stopped. But this did not stop the check battery light from comming on intermittently. And now the car will not start. Any ideas?