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Followup To
Question -
Autohelp, Thanks for your fast response. Tried getting back to you yesterday but your box was full. Did you get my pics I sent to your email?
The answer to all your questions as far as I can tell or remember is NO. I checked all the fuses not long ago and the only blown one was for a fan. I believe it was the secondary cooling fan which comes with the Z52 package. Other elec problems...I've noticed the instrument panel flickers sometimes though nothing crazy. I know the ABS light doesn't come on the inst panel when starting though that's probably unrelated. The horn doesn't work. There's no juice coming up through the column, which I checked recently while installing a new steering wheel. Didn't check the horn relay though...not much else electrical wise. FYI this car is no creampuff and has 90K on it.
I also hear these CS130 alternators can be burned out easily by running a discharged battery. I replaced the battery last year after replacing the first alternator. The battery I replaced was pretty new so I didn't think it would be bad. Turns out it wouldn't hold a charge (probably a bad cell). Maybe I damaged both alternators with that bad battery and the second alt just took some more time to finally die. It doesn't explain the power drain, or humming noise though....
Any more thoughts. Is my wiring correct as far as you can tell?
Thanks again,
Rob
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My questions relate to the wiring of my '87 Corvette alternator.
Background:
I have burned out 2 rebuilt alternators in about 5K miles (as long as I've owned the car). The previous owner (a co-worker / not original owner) told me he went through a few him self and the one I got with the car was relatively new. The last one started making a whining noise and then started smoking. The bearings were fine but both just stopped I got a free replacement which is currently working. I hear the CS130 alternators have reliability issues but I know they can't be this unreliable though. I did some trouble shooting myself to see if anything obvious was wrong.
My findings:
First I noticed I get an approx .4-.5 amp current draw with the current alternator hooked up and also noticed a very faint but audible humming noise from the alternator which goes away after pulling the connector. My plug in connector is labeled S-F-L-P with wires going to S F & L only. There is no I and the P isn't used. After probing the alternator harness connector I noticed it's getting full battery voltage with key off at both the "S" & "F" inputs. The “L” input gets slightly < 12 volts with the ignition on only. Based on info I got on line (see below) The "S" is for sensing battery voltage so that seems right to receive bat voltage. The "F" is supposedly to "send" the ECM info on how much field current is flowing so I don't think it should receive voltage? The “L” is for the “charge light” (I have a digital readout gage). It runs from the ignition switch through the charge lamp and essentially turns the alternator on.
I then noticed the alternator connector wires have been spliced onto wires coming from the harness running fwd along the fender well. A heavy red wire from the harness is spliced to the same which goes to the “S” input and seems correct. A purple wire from the harness is spliced to a black wire on the connector which goes to the “F” input and a green wire is spliced to another green wire which goes the “L” input. This doesn't look stock….especially with the purple spliced to the black. I also noticed above the area the connector plugging into the master cylinder is melted which leads me to believe there might have been a wiring fire at some point.
Is this wiring correct? Do I have the correct connector?
My Haynes Corvette manual only shows a general / non specific charging system wiring diagram which is of no help.
I'd really appreciate any info you could give me.
Thank you,
Rob
Ref: copied on-line info:
"P" Terminal (Phase Connection) - This terminal sends a signal to a relay, frequency sensing tachometer, or computer indicating alternator speed. This terminal may not be used - this is normal.
"L" Terminal (Charge Light) - This terminal is fed from the ignition through the charge light on the dash. This connection turns the alternator "on". Without a signal to turn "on", the alternator will not charge. However the "I" terminal may be used to turn this alternator "on", as described, instead of the "L" terminal. Please note that if there is a connection on the "I" terminal there will be NO connection on the "L" terminal.
"I" Terminal (Ignition) - This terminal is fed directly from the ignition switch to turn the alternator "on". Without a signal to turn the alternator "on", the alternator will not charge. However the "L" terminal may be used to turn this alternator "on", as described, instead of the "I" terminal. Please note that if there is a connection on the "L" terminal there will be NO connection on the "I" terminal. If there is a connection on the "L" terminal AND the "I" Terminal THEN the "I" terminal is NOT an "I" terminal but an "F" terminal (confused yet?).
"F" Terminal (Field Monitor) - This terminal sends a signal to the computer telling it how much field current is flowing (therefore the computer knows how hard the alternator is working). This terminal is not always used AND can only be used if the alternator is turned on by the "L" terminal.
"S" Terminal (Battery Sense Connection) - This terminal is larger than the others and provides the alternator with a precise battery voltage reading however, this connection may not used. When not used, the alternator will automatically sense battery voltage at the battery post.
Answer -
OK, I remember this one. Drove me NUTS for about 15 minutes until using an ohm meter I found the problem.
QUESTION:
1. Are you experiencing any blown GAGE fuses ?.
2. are you experiencing any intermittent speedometer operation ?.
3. are you experiencing any inetrmittent overdrive shuddering effect at low speeds ?.
4. Are you experiencing any intermittent A/C operation ?.
5. Are you experiencing any ufuel injector problems such as an intyermittent miss in the engine.
What other abnormal problems are you experiencing.?.
Think HARD as I need to know the smallest problems.
autohelp
AnswerLet's do the horn FIRST. If you had no battery voltage (juice) up into th sueering column you would have NO turn signals.
The wire that activates the horn is the BLACK wire which is a GROUND wire. If you probe this BLACK wire with a grounded test light the horns should blow. If they do NOT check for battery voltage at BOTH horns while still using the test light to probe the BLACK ground wire going up into the column. If you HAVE battery voltage to the horns RePLACE the horns. If you do NOT have battery votage to the horns, Replace the HORN RELAY.
NO, I did NOT get any pictures that you sent me. Send them to me at:
meperganfortis@msn.com.
autohelp
