Gtpguy

I scanned my car for the ses light that popped up. Its the first since I've owned it. Codes 42-46, 51 53 54 and 55. Some don't apply to fbodies, but all were voltage related. So I did search and found out that innova scanners are worthless on lt1s and give false codes and alternators going out can throw the electrical systems out of wack and throw codes. So I tested it.

Car cold= battery 11.8v
Cold start = battery 13.8 alt 12.6-13.8
Warm park 13.8 alt 13.6
Warm in drive. Braked 0mph. Idling...... battery 13.6 alternator 6-8vts!!

Is my alternator toast?? My idle is pretty weak.
Can the pulled codes, even if they are false, could they pull timing to a safe, zero? My top end has been lacking lately, doesn't pull like it should. But it didn't throw a code until now.
Could it messed with my fuel pump, causing the performance issue? Fuel pressure next I suppose.

GaryDoug

The Innova scanners cannot scan you car. The results you have are exactly what to expect when you scan using an Innova 3120 or similar. The codes are bogus and you have no way of knowing what, if any, real codes you have. either get a better scanner (Actron 9145 or 9185) or get some scan software that can do even more than most handhelds.

https://www.camaroz28.com/forums/com...95-lt1-874306/

Gtpguy

I get that part. What about the low voltage At idle? What about the ses light that's thrown when the Voltage drops that low? Innova might be crap, but that's not what the post is about.

GaryDoug

Sorry, I thought it said "multiple codes..." Eyes must be failing me.

Injuneer

Confusing..... not sure why this got posted in "Fuel and Ignition"?????

Moving.

Gtpguy

I figured the alternator was part of the ignition system. My bad. Maybe now someone can answer my question now that it's in the right forum.

shoebox

Simple enough to have the alternator tested. You shouldn't ever see 8v.

Gtpguy

I don't mind having it tested at autozone, but if they test it cold, wouldnt it be a false negative? I'll ask them to test it 4 times back to back.

GaryDoug

The FSM shows the Batt terminal of the alternator connected directly to the battery positive. You guys with a real car can confirm or refute that. If that is true and there is a 8 square mm (AWG8) cable between those points, this must be breaking Ohms law with 4 volts dc between the ends unless that cable is bad.

shoebox

Yeah, I'm not understanding that, either.

Injuneer

I was hoping you'd respond to the 8V. I looked at that and my response was going to be "are you sure you read the meter right?". I didn't think that was possible.

Gtpguy

It was between 6 and 8 volts hot. Believe it or not, it's true. Cars fine cold, took volt readings, car gets warmer, battery stays fine (optima, don't know if that makes a difference, at this point who knows) then the alt gets hot and only pumps out 6 to 8 and BAM!!!! DTC.

Gary, you think that cable can be shot?

GaryDoug

Try taking the measurements again warm. This time, measure the voltage between the battery positive terminal and the generator outputs (Batt) large wire terminal. Also measure the voltage between the battery negative terminal and the alternator's metal case. Both measurements in a normally working car should be less than 0.5 volts. If either measures much more than that, either the cable is bad or the car has been rewired differently from stock. It is possible I suppose that the engine ground is opening, but it seems that would stop the engine (?). Otherwise I see no other reason except an open Batt wire.

GaryDoug

I just ordered an Innova 3120d scanner (which I plan to return to Amazon) and will test it on my 94 LT1 PCM bench setup. If it doesn't work, I will find out why not and see if I can find a workaround. Stay tuned...

Gtpguy

Positive/alternator .1 to .3v depending where I put the needle. .1v on the actual wire, .3v by the nut.

Neg/case -.07. If I put the needle on the black wrap around part of the case, it jumped up more.