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Car off, +/- on battery: 12.6V
Car on, +/- on battery: 13V
Car on, DIC: 13V
Car on, +/- on alternator: 14.9V
Car on, + on alternator, - on vehicle ground: 14.9V
Car on, + on battery, - on alternator: 13V
14.9, alternator is fine, and the ECM has it cranked since it not getting enough power to the ECM instead, and why it not just 14.6V.
From battery ground to alternator ground as your ground points, I'm not seeing any differences in voltages, and it looking like either the positive wire connection points at the starter solenoid for the two positive wires, or the thermal fuse in line just before the starter solenoid for the positive wire coming off the alternator.
P.s. still waiting on the reading from the engine fuse block terminal, to the alternator ground with the motor running.
So the 4 readings I needed again with the motor running and the AC off
At the alternator only, (14.9)
At the battery terminals only, (13.v)
From the positive terminal (not the wire connector) on the engine fuse block to the body of the alternator as the ground point. (don't have this, but with the battery and DCI the same, will guess that the connection there is good)
The DCI voltage (13 volts)
As for battery, a fully charged battery will put out around 13.7 volts. The fact that your is not putting this voltage out with the car off, is the battery is not getting fully charged to begin with (not seeing 14.1+ volts).
I just tested it again and found the following results:
Car off, +/- on battery: 12.6V
Car on, +/- on battery: 13V
Car on, DIC: 13V
Car on, +/- on alternator: 14.9V
Car on, + on alternator, - on vehicle ground: 14.9V
Car on, + on battery, - on alternator: 13V
So basically I'm losing 1-1.5+ V on the positive somewhere between the alternator and the battery. I think we can safely say it's positive issues and not ground issues. Can we rule out the spark plugs yet, or should I still swap in OEM ones? The starter looked okay but I wasn't able to test voltage there.
We finally figured it out today! The engine was not completely grounded to the chassis / battery. As a result, I'd get random voltage dips and the occasional Service ABS System when it got too low.
I finished up testing it today the way Dano described. I noticed that alternator was still 14.8V+ out when measuring +/- on alternator. The battery was still about a volt and a half lower, measuring 13V. I then measured positive on battery, and negative on engine, and noticed it was 14.5V!
We borrowed a grounding cable and temporarily held it to the engine block and the chassis. And what do you know... 14.4V at the dash, constant. Remove the cable, it drops down to 13.5V.
We will be adding another ground this week.
Posting up in case any others run into this issue. Just be sure to measure +/- in various places to isolate.
I use power master high torq starter on both my 13. To one compression 440 ci ls7 and in my 14.1 to one ls3.
We boost just about every thing else and not the starter?
The only one to consider is the 4 to 1 gear reduction 18 to one compression rated and put a blanket of some kind over it.
We finally figured it out today! The engine was not completely grounded to the chassis / battery. As a result, I'd get random voltage dips and the occasional Service ABS System when it got too low.
I finished up testing it today the way Dano described. I noticed that alternator was still 14.8V+ out when measuring +/- on alternator. The battery was still about a volt and a half lower, measuring 13V. I then measured positive on battery, and negative on engine, and noticed it was 14.5V!
We borrowed a grounding cable and temporarily held it to the engine block and the chassis. And what do you know... 14.4V at the dash, constant. Remove the cable, it drops down to 13.5V.
We will be adding another ground this week.
Posting up in case any others run into this issue. Just be sure to measure +/- in various places to isolate.
Doesn't this mean that one of the grounds on the block is probably loose or corroded or both?
Ground point from the engine to the battery negative cable.
Which means that they just need to get under the car, remove the ground connection point bolt to the engine from the battery cable, clean up the connection point on the block, the cable loop connector, and make sure then when the end of the cable loop is bolted back to the engine block, it's tight and clean, and some dielectric grease in play so it does not corrode so quickly again.
Hence one of my alternator/charging system tests for battery voltage is to first check the battery terminals directly alone, then to use the alternator as your ground point next. if using the alternator body instead of the battery terminal lug yields the higher needed voltage, then you know that the battery cable ground to the engine block point show above is suspect to begin with/needs to be addressed.
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