parasitic drain problem

[Simca]

Hey guys i have a 1990 240sx hatchback with a rb20det .

when i check the battery with a meter it reads around 11.90 to 12.60 volts
. When i run the engine its only reading 11.60 and slowly drains on an idle.
When i drive around the block it drains extremely fast and dies before i getr around and i have to jump it to let it charge a bit to make it home.

I thought it was a bad alternator so i swapped it with another, exact same alternator ran the number with napa. once i ran the the new alti all my electronics died i checked the fuses and found that my fl75w/alt fuse and fixed it all my electronics are working now. but i still have the parasitic issue, maybe you guys have a clue wtf is wrong with it, please leave your comments and suggestions .


thanks in advance

[Sileighty_85]

a properly charging system you should have around +13.5ish
a properly charged battery will have around 12.5V

So it doesnt sound like a drain it sounds like your charging system is not working properly

double check all grounds and connections especially around the passenger side fuse box on the side of it

[murda-c]

Are you battery terminals corroded?

hit them with a wire brush and then see if that works. I had the same problem with it not charging even with a working alternator.

[Simca]

Battery is brand new and fuses are all good as well as all connections.

[Sileighty_85]

check the voltage off the Alt +

If you got 13+V then you missed a connector

[P-Funk alot]

there should be a small ground wire on the alternator make sure this is there and properly secured to the alternator. also check your lower harness. i had the ground wire issue before did the same thing

[Simca]

It's reading the exact same reading when the engine is running

[Simca]

i put a new battery in today ready 13.7 at charge with meter when i put it in the car its reading 11.76 and slowly drains awasy when its on idle but if i drive it it dies in 5 minutes, ugh this is killing me cause i have no way to pull the engine atm and my car is shipping to my new house in tx soon . please guys if you got any ideas please lemme know

[FrippS]

Have the same exact problem......have you had any luck? Does your battery light on the dash come on at all?

so damn frustrating.

[PoorMans180SX]

If the voltage reads the same when your car is running, your alternator is not working. You have something connected wrong.

[FrippS]

ok, assume it is hooked up properly...

car off= 12V or more
start car= 11.5 approx
then will trickle down slowly, also will sputter if u drive it. only intermittently sputtering though. very inconsistent. no battery light ever. 75amp fuse is good, battery in trunk with 0gauge cable. main grounds are not frayed or old or fried. dunno, had a bunch of people check it out,

could i pull codes from the ecu??? will it tell me?

[PoorMans180SX]

No it won't tell you. There should be 13+volts at the battery at all times with the car on. Your alternator is not functioning.

[FrippS]

any ideas of what could be hooked up wrong? cause its not the alternator, that is hooked up correctly, is there an external voltage regulator somewhere that can be bad, alt/batt are good had them tested before and even took them back out and tested to make sure its not frying the alt.

[Sileighty_85]

the VR is built into the alt. if the Alt is hooked up properly and grounded and your not getting 13+ volts from the alt, then the alt is bad...

Or it has been wired up incorrectly. what lower harness are you using?

[FrippS]

its an sr hasrness.
u know anything about a "sense line" someone says that if the battery light on the dash is bad, it wont complete the circuit for the sense line to tell the alt there is low voltage????

[bartdog]

Here's the dealio.... Big wire that bolts to alternator post should measure same as battery voltage at all times.

The two wire plug/connector; bigger wire(usually white) is the alt sense circuit... should also be same as battery voltage at all times.

Smaller wire of the connector is the "turn on" or excitation circuit. This should have power (usually somewhat less than battery voltage) ONLY when the key is "on". This circuit does come from the battery warning light. Key on power to one side of the bulb... the other side of bulb goes straight to alt. If no power to bulb or blown/missing bulb or open circuit in wiring from bulb to alt. then no "excitation" = not charging.

Are other warning lights coming on with key on / engine off?

So first step.... is battery light on with key on / engine off?

[FrippS]

yes that makes perfect sense. i have got it fixed, battery light was not coming on period. there were 2 wires that were not connected behind the fuse box under the dash on the drivers side. now they are connected And the alt is charging and the batt light comes on when u turn the ignition on. thanks for the info