tommya29

hi yall i have a 2002 malibu 123,000 miles.other than the abs and brake lights coming on it runs great except when i turn the ac on it revs up a little run good then just stalls out if i am driving it wont do it until i let off the gas then it doesnt want to restart even with ac turned back off i have to press gas pedal and crank a few times to get it going.

id appreciate any help i never worked on these cars before im not real familiar with their electronics

tommya29

well ive had it scanned only codes it had was abs low voltage and egr closed i replaced the egr and still every time the compressor turns on the rpms surge up and down and it just stalls out

i did notice now tho when on the gas with compressor on it surges a little then but doesnt cut off till i let off the gas.now tho without ac on just driving if i come to a stop when i go to take off rpms drop when i hit the gas like its going to cut off and then they jump and car takes off im starting to regret buying this car

EinST

It sounds like you inherited someone else's headache. It would help if you posted the actual trouble codes rather than some cryptic interpretations. So, you replaced the EGR valve but with what (brand, used/new, etc.)? How's the fuel pressure? Check the fuel pressure regulator for fuel leaking through the vacuum port?

kevinkpk

Yes, I agree on both points.

tommya29

sorry it has taken a long time since my last post i have been unable to drive my car to get codes from autozone my egr was a delco i think brand new i have checked regulator and vacuum and everything looks ok. my car however is down now due to alternator.

here is where im getting mad it was charging then out the blue it wouldnt on n off for days finaly it does nothing so i replaced it twice now i get 12.22 vdc at battery and 1.6 vdc at alternator i ohmed out charging wire to to 5.9 ohms i really dont get it

and now my service vehicle soon lite is on and gotta hold key and crank sumtimes for 10 second just to start it even had to pat gas once cause it was shutting back off. it seems to be electrical to me either cuz i just dont know enough or cuuz i just wish it was one problem

i have no idea what to do i know i dont have alota tech info cuz i cant get car to drive without alt working my battery is toast now wont hold charge ide appreciate a point in the rite direction

edit:also i forgot i did check engine to battery ground and to frame its .8 ohms

EinST

Which terminal did you measure 1.6V and against which ground? Did you check the 10A GEN BATT fuse in the underhood fuse block?

tommya29

first i did battery to output (red charging wire) then motor to same terminal.i just got off work and checked that fuse its good.im wondering if 6 ohms is to high for that wire but wouldnt i have output from alternator even if it wasnt good? or does the rectifier need to have voltage to work? this thing got me really stump.

my bro in law came by he got one of them walmart scanners he didnt leave me the codes like i asked but said almost all of them said sumthing for low voltage.im wondering if this is all thats been wrong with my car. but nothing came up about charging system i was hoping that would be what turn my service vehicle soon lite on

EinST

No, you can't isolate the alternator from the battery. The battery actually powers the field windings in lieu of permanent magnets. The way it works is, the L Control circuit (that's the thinner of the two RED wires) from the PCM tells the regulator to turn on. The regulator then has to see the reference voltage through the GEN BATT fuse (ORG wire) to control the generator. When there's a problem, the regulator grounds the F Input circuit (GRY wire) to the PCM which then turns on the battery warning light.

Now the correct way to test is, measure the voltage across the battery with the engine off and then with it running (1500-2000 RPMs). With the engine running, the voltage should be .5-2.5 volts higher. If not, you may indeed have a defective alternator or you may have a PCM problem (L Control circuit).

tommya29

thank you very much tho as an electrician im a lil embarassed this car beat me up so bad after you explained it i took my meter to it tested all my wires even took fusebox apart to look for loose connections

ohmed out charging wire foot by foot til i got to starter.i happened to look down and saw my red wire was black it still ohmed out good i took it off anyways to discover all but 2 strands were burnt off.i felt so bad to have missed that.i fixed the connection and ohmed out the wire from battery terminal to alt and it was0.1 ohm started car and 14.6 volts voltage drop is less that .3 volts.

im so happy thank you so much for your help

for sum reason i still have my abs and brake lites and service vehicle soon and check engine lite ill post my codes as soon i can get down to have it scanned hopfully it works out like this did

ahmaduhhs

remove the negative battery cable for 10-15 mins then re-attach it and the ligth should turn off