07 mustang gt low voltage at idle under load in gear

965

Asked by coolslider Jul 22, 2017 at 09:39 AM about the 2007 Ford Mustang GT Deluxe Coupe RWD

Question type: Maintenance & Repair

to start I am now on my 5th alternator they have all started failing one after the other.

1-3rd alternator fried the regulators
1st regulator went out on highway at 65mph
2nd and 3rd at stop light with AC on and headlights on in 1st gear (Automatic Trannsmission)
4th rectifier bridge failed diodes crispy
5th regulator same as 2-3rd scenario

all 5 alternators have been in the last 6 month. orange wire has bat voltage on 3 pin pigtail other 2 have no voltage gencom and genmon labels

Problems do not appear when vehicle is cold only when warmed up
7 am to 7:30 drive to work no problem
4pm on when 85 degrees outside this happens
Load refers to AC headlights and radio
at idle no load out of gear no breaks13.6-14.1v
at idle with load out of gear with breaks13.4-13.6
at idle with load in gear 12.6-12.7
idle load gear and break lights 12.2-12.4

cleaned throttle body(cannot clean iac as sealed to side of throttle body 2007 model) cleaned MAF sensor, checked for vacuum leaks, belt is not slipping, 0/0 gauge ground wire installed between alternator housing and frame, battery to ground wire 8 gauge installed.

when cold idle at stop light in gear with load on idle is 680-720
when warm idle is 550-600 in gear under load during breaking applications




2 Answers

965

new alternator is from autozone and it is having the voltage drop again I have to shift to neutral at stop lights or risk frying another regulator I have also looked for shorted wires and cannot find any im at a loss hear I have automotive degree dad is ase master certified and even the for dealership is scratching there heads at this one

1 people found this helpful.

Your Answer:

Own this car?

Share your experience with others.

2007 Ford Mustang

Review another car

CarGurus Experts

  • #1
    Gene Arnett
    Reputation
    3,160
  • #2
    Bob Beaman
    Reputation
    2,690
  • #3
    rst429
    Reputation
    2,640
View All

Know more, shop wisely

Search

Related Models For Sale

Used Chevrolet Corvette
793 Great Deals out of 14,532 listings starting at $4,999
Used Dodge Charger
819 Great Deals out of 14,534 listings starting at $2,500
Used Dodge Challenger
700 Great Deals out of 11,819 listings starting at $5,995
Used Ford F-150
6,461 Great Deals out of 169,177 listings starting at $1,871
Used Ford Mustang Shelby GT500
39 Great Deals out of 586 listings starting at $23,995
Used BMW 3 Series
1,009 Great Deals out of 14,193 listings starting at $1,200
Used Chevrolet Silverado 1500
4,160 Great Deals out of 123,229 listings starting at $1,999
Used BMW M3
81 Great Deals out of 1,485 listings starting at $9,888
Used Honda Civic
1,297 Great Deals out of 26,038 listings starting at $997
Used Lexus IS
298 Great Deals out of 4,977 listings starting at $1,500

Used Cars for Sale

2024 Ford Mustang For Sale
99 Great Deals out of 7,395 listings starting at $24,890
2023 Ford Mustang For Sale
38 Great Deals out of 561 listings starting at $20,900
2022 Ford Mustang For Sale
86 Great Deals out of 1,130 listings starting at $14,418
2021 Ford Mustang For Sale
81 Great Deals out of 1,009 listings starting at $16,899
2020 Ford Mustang For Sale
84 Great Deals out of 972 listings starting at $14,326

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.