I have a 88 Trans Am TPI 5.0 engine and engine harness in a 87 Trans Am Body. The brown wire or the L PED does not have power when the key is in the on position so therefore my alternator does not charge. the brown wire goes from the alternator to the cluster gauge. I took the instrument panel off so it shows just the 2 connectors in the back and i checked for resistance from the wire up at the alternator to the instrument panel on C2 number 12 in the back of the dash where the instrument panel hooks up to and the resistance is 1.2 so if its that, then there should at least be some voltage up front. i know all 3 of those wires up at the alternator are suppose to have power when the igntition is in run. Is there a way to run a new wire or just tap power into that brown wire and it would work? What else can i do to fix this? Thank you!
-
-
By chance is your Check engine light burned out? If memory serves me, those years relied on the check engine light in series to complete the circuit. If the bulb burned out or the cluster was disconnected, the alternator wouldn't charge. I can't be 100% sure if your model is affected, but it's worth looking at.
-
Also you need to perform a voltage drop test instead of a resistance test. A resistance test is worthless in proving or disproving voltage loss related to alternator output. A single strand of wire will show the same resistance as the whole wire intact. The only thing a resistance test will show is if the wire is completely cut or if there was a 100% short circuit.Comment
-
the check engine light does work so its not that and the voltage for that wire is 0.0 volts when the key is in the run position. The output voltage of the altenator is 11.8 volts and thats what the battery is also when i check for voltage on the battery too.Comment
-
That is a very low voltage output. So low in fact, that is probably a indicator that your alternator has given up. If you suspect the alternator, Pull the alternator and take it to your local parts store and they will load test it for free.Originally posted by chevelleman_04
Check your battery as well. The #1 cause of a killed alternator is a weak battery. It puts too much prolonged strain on the alternator.Comment
-
well i took the car to a local parts store to have them test the charging system and the alternator was putting out 10.5 volts and it said Diods checked good, im still thinking its that brown wire thats named L on the conector of the alternator plug. Does that wire need to have power for the alternator to charge? I do not have an indicator light on my cluster and the bulb isnt out, my cluster gauge just doesnt have a indicator light for the voltage. I think the 88 trans am that the engine was in might of had an indicator light and now that mine doesnt it wont charge?Comment
-
If the diodes passed then the alternator is probably good it's just not being .Yes, you need 12V to the brown wire in order for the alternator to charge. Most of the accesories and stuff like radiator fan, power windows, and windshield wipers get their 12V source straight from the ignition switch. It's been awhile, but if I remember correctly, that was an orange wire. Anyway, my point is that I believe that brown alternator lead gets its 12V from the ignition switch as well....it may lead straight to the battery as well.
If you have the 4 pin connector, that brown wire is the "S" wire. The battery sense wire. Te alternator must sense an external voltage level before it will start to supply a charge to the battery. The battery sense wire also dictates how much voltage is allowed from the alternator.Comment
-
had an 88 firebird and i agree with joe because i had that bulb burn out on the car and had to replace it for the alternator to charge1991 Pontiac Trans Am V8 305Comment
Comment