Low voltage, even after new Battery and Alternator

[drallan]

2004 v8 w/ 325K.

Got a new daily driver with better mpg and the 4runner has been relegated to camping trips, and other messy activities. I try to drive it a few days a month, but this summer it sat for about 2 months without any activity.

When I last drove this summer had no issues or lights. Went to drive and get ready for upcoming camping trip the other day and had the battery light come on. Started up no issue and drove fine for a few days. Torque was showing about 12.6V through OBDII.

Replaced battery and alternator this past weekend and no change. Drives fine, starts every time. I've cleaned and checked all the connectors and grounds I can see. Multimeter shows roughly 13.4-13.6v when touching various contacts around the battery, battery post, battery connector, fender ground, fusebox, etc.

Next on the list is to change out the cable terminals. I have not done the big 3 upgrade (would like to avoid if possible as this is just and occasional weekend use vehicle). Looks like there is a big cable that runs down under the engine block. I tried tracing it best I could under with skid plates off, but didn't have much luck. I have a small valve cover oil leak and some gunked up oil spillage from oil changes.

Only thought I had was that oil has dripped down and cause an issue to whatever connections are on the underside.

Does anyone have a good engine diagram with all the cables, grounds and connections I can check that aren't readily visible on top?

Is there a separate voltage regulator? looks like what could be a voltage regulator (black block w/ fins) on the driver side behind fuse box, but I'm having a hard time finding more details on it. I thought the regulator was built into the alternator.

Any thoughts?

Thanks',

 

[Ripper238]

Sounds fine?

 

[drallan]

Driving fine, but the battery light stays lit on the dash, so somewhere in the system it is registering a low voltage. That is what prompted me to do something. I was going to drive it all week and see if it resolves itself, but I monitor the voltage through Torque and am constantly between 12.5-12.7 volts. Sometimes it dips down to 12.2-12.3 idling at a light, but never seems to go above 12.8. Hoping it is just a bad / dirty connector / cable somewhere but just don't know where to look other than the obvious ones visible in the engine bay.

 

[xtremewlr]

Check and clean all the grounds that you can find. Dirty ground could also be causing you issues.

 

[drallan]

Check and clean all the grounds that you can find. Dirty ground could also be causing you issues.

Yes, thank you. I have checked and cleaned the grounds I can find, but is there a diagram or list of grounds that may not be obvious? I've done all the ones I can see around the battery box, top of engine / manifold and alternator. I can't seem to find where the big block ground is, there is a protected wire that looks pretty decent gauge that goes down and under the engine from the battery (one of the big 3?), but I'm having a difficult time locating where it bolts to the frame/engine.

Anyone else run into this or have pictures of the grounds? Assuming the big cable from alternator runs directly to positive side of battery, or is there a splice somewhere in between?

Since she starts up fine I wasn't going to pull the manifold off to get at the starter.

Where does the cluster read the voltage from? I'm guessing at the ECU near fuse box? Are there other wires in that area that aren't obvious?

 

[MikeinNH67]

So the ECU sees close to a volt less than what you read with a meter at the battery? If so you'd have to try and locate where that voltage drop is. Should be able to hunt around with a volt meter to see if the ECU is getting an accurate reading, hopefully it's not the computer itself. I think the first thing I'd try is running a wire from the battery ground right to the ground the ECU is using. Yeah a schematic would help but I don't know of one you can just grab online.

 

[gaber6]

So the ECU sees close to a volt less than what you read with a meter at the battery? If so you'd have to try and locate where that voltage drop is. Should be able to hunt around with a volt meter to see if the ECU is getting an accurate reading, hopefully it's not the computer itself. I think the first thing I'd try is running a wire from the battery ground right to the ground the ECU is using. Yeah a schematic would help but I don't know of one you can just grab online.

Main ground cable is likely corroded on the inside. I just helped jump a car recently and it would jump then barely stay running and showed low voltage even though she had a new alternator and battery. I ran and got her a $15 cable and it perked right up.