voltage is wrong after alternator swap

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
rhandle said:
sorry to bother you . I asked a question that no one had an answer . I had a svc charging system warning and voltage dropped to 10v . bought new battery but no change .dealer changed alternator but since then TROUBLE. The volts on dash r reading incorrectly loe 11.9 to 12.8 ,.both gauges . At battery volts r correct at 13.4. Prior to this both gauges were 100% accurate and matched voltmeter . Is it the new battery or a faulty alternator. Sorry to bother you but i need help . I will be happy to pay you for your time if necessary thanks RICHARD

as always it helps to have a shop manual for your year and model car, then I'd suggest, you get out your multi meter and verify the alternator is putting out about 14 volts while the engine runs,pull the trouble codes with a code reader, then check the electrical grounds and fuses as a first step, in isolating the problems source


reading these links will be helpful
yes I know it will take some time and effort to isolate and test

but its the only 100% sure route to finding and fixing your problem,
don,t get over whelmed,
simply break the problem down to testing each basic sub system,
test each related sensor and electrical component and electrical sensor and connection.

some reading on the threads posted below, a bit of logic and deductive reasoning, and a multi meter and a shop manual will go a long way toward finding and fixing the problem.


Measured Value
Engine Coolant Temperature Sensor. 185 Ohms @ 210F, 3400 Ohms @ 68F, 7,500 Ohms @ 39 F.
Engine Oil Temperature Sensor. 185 Ohms @ 210 F, 3400 Ohms @ 68 F, 7,500 Ohms @39 F.
Oil Pressure Sender/Switch. 1 Ohms @ 0 PSI, 43 Ohms @ 30 PSI, 86 Ohms @ 60 PSI.
Fuel Quantity Sender. 0 Ohms @ Empty, 45 Ohms @ 1/2 Full, 90 Ohms @ Full.
MAT (Manifold Absolute Temperature Sensor). 185 Ohms @ 210 F, 3400 Ohms @ 70 F, 15,000 Ohms @ 40 F.
Outside Temperature Sensor. 4400 Ohms @ 60 F, 2200 Ohms @ 85 F.
In Car Temp Temperature Sensor. 4400 Ohms @ 60 F, 2200 Ohms @ 85 F.
MAF (Mass Air Flow) Sensor. .4 Volts @ idle, 5 Volts @ Full Throttle.
Oxygen (O2) Sensor. .1 Volt Lean Mixture, .9 Volt Rich Mixture.
TPS (Throttle Position Sensor). .54 Volts Idle, ~ 5 Volts Full Throttle.

Sensor Locations

Sensor


Location
Engine Coolant Temperature Sensor. Front of engine, below Throttle Body.
Engine Oil Temperature Sensor. Left rear of engine, just above the oil filter.
Oil Pressure Sender/Switch. Top, left hand rear of engine.
Fuel Quantity Sender. Top of fuel tank, beneath filler pipe escutcheon panel.
MAT (Manifold Absolute Temperature Sensor). Underside of manifold air plenum at rear.
Outside Temperature Sensor. Right side of engine, top right corner of radiator.
In Car Temp Temperature Sensor. Coupe: above left seat near interior courtesy light, Convertible: center of cargo compartment lid.
MAF (Mass Air Flow) Sensor. Front of engine ahead of throttle body.
Oxygen (O2) Sensor. Left side of engine, in exhaust pipe.
TPS (Throttle Position Sensor). Right side of throttle body at the front.


image_6238.jpg

this is the most consistently accurate I.R temp gun I've used for testing[/img]
42545.jpg

http://www.testequipmentdepot.com/extech/thermometers-and-humidity-meters/infrared-thermometers/high-temperature-infrared-thermometer-58to1832f-50to1-laser-pointer-42545.htm?utm_source=bing&utm_medium=cpc&utm_campaign=NEXT - Bing Shopping - Extech&utm_term=1100200223789&utm_content=All Extech Products
INFRARED TEMP GUN
you always need a base line to start from, on a corvette.
a logical step by step approach and keeping accurate notes helps.

youll NEED a multi meter, a shop manual
and a timing light and fuel pressure gauge at a minimum,

set and verify your ignition timing, pull trouble codes,set your tps and iac,, then check for vacuum leaks on the lines and intake,then get out your multi meter and verify all the sensors, chances are good a logical step by step approach will lead you to the problem, youll be amazed at what youll learn reading links. use of a shop manual and multi meter can be very helpful
1996_Corvette.jpg



http://garage.grumpysperformance.com/index.php?threads/testing-an-alternator.3222/#post-46703

http://garage.grumpysperformance.com/index.php?threads/is-my-alternator-shot.7808/#post-26803

http://garage.grumpysperformance.co...4-started-running-like-crap.10970/#post-48278

http://garage.grumpysperformance.com/index.php?threads/cs-144-troubleshooting.12494/

http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-43477

http://garage.grumpysperformance.co...ood-alternator-putting-out-low-voltage.12221/

http://garage.grumpysperformance.com/index.php?threads/battery-or-alternator.10003/#post-43220

http://garage.grumpysperformance.com/index.php?threads/c4-c5-corvette-trouble-codes.2697/#post-69239


https://store.alternatorparts.com/cs144-series-200-amp-extreme-duty-dual-rectifier-alternator.aspx

http://garage.grumpysperformance.com/index.php?threads/electrical-puzzler.13038/#post-67835

http://garage.grumpysperformance.co...questions-can-be-found-here.12892/#post-66934

http://garage.grumpysperformance.co...hink-logically-don-t-assume.12484/#post-62772

http://garage.grumpysperformance.com/index.php?threads/multi-meters.3110/#post-59136
 
Last edited:
Back
Top