MD3K

Last week my battery light came on and speedo starting going haywire... thought it was alternator so put in a new one. Same results, so i have check and cleaned all grounds, checked ELD, checked all fuses. Dug in further and im not getting battery voltage on the IG wire on 4p alternator connector. I do have continuity from fuse 4 to ELD but open between alternator connector and fuse and open between alt connector and ELD. Does anyone know where the IG wire connects to the circuit or what else is on this circuit that could be breaking the circuit? I am looking for the best place to start tracing the circuit.

ezone

black/yellow wire

remove plastic trim from valve cover

locate two large rectangular blocks with lots of wires, these are splice packs or junctions for several circuit branches

the block between coils 2 and 3 should contain several of the black/yellow wires. That would be a likely place to do the next continuity check (between these wires and the alternator).


Do you have any fault codes? Knowing what they all are might give a clue to where a break might be.
All of these share the same fuse, but not all branch from this splice pack:
ELD
cruise
O2
AF
EVAP CVS
EVAP BP
EVAP purge
Alternator
VSS

MD3K

I will look into the splice pack today. I do have a code for the downstream O2 sensor... And i have confirmed continuity between alt., downstream 02, VSS, and 1 of the Evap connectors. will check the other items today if the problem doesn't turn out to be in the splice pack. I appreciate the help, will post back results...

ezone

Instead of checking continuity, I prefer to look for correct voltage with the system or circuits powered up.

Loaded circuit testing can reveal problems that ohm checks cannot.

MD3K

Ok so I had battery voltage on one wire in the splice pack with the connector bus unplugged... with it plugged in (connecting all the wires) voltage drops to 3v... so i jumped each wire individually with the power wire to see which wire was causing the issue...turns out its the wire to the alt plug. With alternator plug disconnected from alternator, i get battery voltage.... this leads me to believe there is a short in the alternator... would i be correct or could it be that something is wrong with the ecm, and its causing something to get squirrely only when the alternator is plugged in? This is the second alternator i have tried, but it is reman from advance...although i did have them bench test it...also i forgot to mention that yesterday i jumped a wire from the alternator plug directly to battery, and got the alternator to charge and battery light to go off...

ezone

See, voltage checks on a live circuit reveal far more than ohm checking an unloaded circuit.
No, cannot be the ECM.


You're dealing with 12v that's missing.

If the alt had an internal short--- the fuse would blow. Agree? Good.

So back to this line: That's gonna be your power 'source' wire that starts at the fusebox in the dash.

With all of the splice pack wires connected, that particular source wire also drops to 3v, yes?

You've got high resistance causing voltage drop. Now you gotta find where it is.
Now you need to trace that one wire back toward its source....

Lets measure voltage someplace that's easy to reach first:

With everything connected again , keyed up turned on and measuring 3v at the splice pack, probe voltage on the top of the fuse and see what both sides of the fuse show.
(dash, fuse #4, 10A) You DO know the fuse has open tabs on top for testing while installed in the box, yes? Use them.


If the voltage checks LOW at the fuse, skip everything below and holler at me

Assuming the fuse still shows full battery voltage.....


If it's easy for you to check the plug on the bottom of the ELD in the engine compartment fuse box, see if the blk/org wire in it shows correct voltage or not.
If it measures 3v like the bunch of black/yellow wires, I'm gonna send you to check connections on the dash fuse block.
If it's proper 12v then proceed as explained below.


So if you got 12v on the blk/org wire on the ELD, but 3v at the splice pack of blk/yel wires.....problem area is likely to be the connectionsbetween fuse and splice pack (poor contact, high resistance)

and a good possibility is in the harness connector C101 near the ECM (and it's easy to get to)

C101:



From the fusebox the wire color is black/orange, and it changes to black/yellow as it passes through this connector....my diagram says it's terminal position 17

Find the wire, use a paper clip to backprobe each side of the connection to see if it's high on one side (blk/org) and low in the other (blk/yel)...and if you managed to make the problem disappear while touching this connector, the problem is probably inside this connector so open er up and check it out



===============

I'd have a voltmeter meter propped up where I can see it while I work under the dash....one lead connected to the fuse #4, other lead connected to a blk/yel wire in the splice pack OR backprobed into the alternator connector (still plugged into the alternator) so I can see when the voltage drop changes as I work.

With the meter connected this way, I figure it will show about 9v (12v battery voltage minus the 3v found at the splice pack equals about 9 volts lost between the two points...that's measuring the "voltage drop". Once the high resistance is gone (probably a bad connection that will get fixed) the meter would show near or at zero volts once the bad connection is restored and no voltage is lost through the connection.

==================

Holy crap.
TL;DR
see if there's a burned terminal inside that gray connector shown in the picture

MD3K

Checked the C101 connector and it was not quite connected all the way. snapped it back together and the 9v i was reading between fuse 4 and spice pack went to zero.... so i got voltage back at the alternator but when i cranked it up voltage dropped back down, turned out to be the power from fuse and alternator pins in the splice box not making good connectiions, so i took the pins out and pinched down the tab to make better connection and now everthing seems to be working right.... appears the problem was both at the c101 connector and the splice pack... thanks for the help ezone

ezone

Holy cow, that hour I spent composing the reply actually went to good use! LOL

Who would have left the connector in the dash half undone?

Good to hear you got it fixed. Have a blessed day!

MD3K

Update,
After driving around a little the battery light will momentarily flash but does not stay on. I have done did some more testing and with the car cranked the alternator would charge for a few minutes then cut off... battery voltage would drop below 11v and alternator would not come back on... took battery to advance for testing and tested to have a bad cell. So, I put a new battery in it, and alternator works but battery light still intermittenlty flashing. I took loose the connections in the splice pack and behind glovebox and soldered together to eliminate possibility of bad connections there, and also added an extra ground wire to the alternator body from the frame ( thinking maybe i had a poor ground connection as the top alternator bolt was crossthreaded when i first started this whole deal... I also ran wires from ground on body and alternator output bolt and alternator IG wire so that i could hook up two voltmeters at the same time to see voltage on the alt output and IG input while inside the car with it running... result is that alt output was 14.4 to 14.9 while idling and up to 2000 rpm. I was able to get the battery light to flash momentarily a couple times and noticed that is flashed only when voltage jumped over 15v - up to 15.5 one of the times. Meanwhile the voltage on the IG wire remained a steady 13 volts the entire time (second voltmeter only reads whole numbers). This leads me to believe that alt is overcharging intemittently and causing battery light to flash when that happens? Would there be anything else that would cause this other than alternator having faulty voltage reg, or am I even on the right track?

ezone

Back to standard basic warning light troubleshooting then?

See if alternator is the one in control of the warning light. The alternator is supposed to be in control of the light, but it's done via other control units (PCM, MICU, gauge cluster) so any of them with a fault could also keep the light on.

If you can get the (battery symbol) warning light to stay on while the engine is running, simply unplug the alternator 4 wire connector and see if the light turns off.
If so, alternator is the culprit.
If warning light remains on, something else is keeping it on.

Charging voltage over spec should be a voltage regulator problem.....and if charging voltage happens to exceed 16v the SRS warning light should turn on, but leave no fault codes.