*HELP* Voltage drop for dash/obd2 connector

[mrjd1981]

Hello. My first true post here, but I have been a long time gawker at these forums. You have all been a great source of information to help me through the issues i've had with my explorer. But I think I may finally have a new one.

A few weeks ago I noticed the battery gauge on my explorer slightly lower then nominal.

My first instinct was battery. So I tested the battery I had and it did come up as bad according to my B&D Smart charger. I replaced the battery. But the problem did not go away.

My second thought was Alt. so I grabbed my volt meter and its testing at 14.3-14.5..........Scratched that off my list.

So I thought maybe a ground wire or something along that line. I removed all ground bolts, sanded leads and surfaces where they attach, and used new bolts. As well as sanded surfaces on the starter where the large neg attaches. No results.


So I decided to run positive lead on my multimeter to the cig lighter, and negative to a purple wire on the obd connector and it comes up saying 13.1v...

I trace the wire all the way back to the ECU and the solid purple wire coming out of near the center of the ECU. I stuck a pin in the wire and tested it at also 13.1 while running.

Any idea what this wire is, or why this wire from the ECU would be only at 13.1 and not the full 14ish?

Any other ideas why I would not be getting full voltage to dash/obd2.

I am about to replace the alt just to scratch that off the list. next I guess would be the ECU but I've never messed with those before.

 

[mrjd1981]

I forgot to mention, one day while driving in the rain the speedometer decided to tweak out like it was smoking something that is bad........m'kay

And when I try the hazards out the voltage needle jumps from just below normal (bottom of battery on gauge) to about 25% and back

Oh and i checked instrument panel fuses..........a'ok

 

[budwich]

probably a dumb question but what exactly do you think you are chasing and why?

 

[mrjd1981]

I guess I didn't explain the severity of the spedo jumping around. that was not all that happened. with the spedo jumping it also decided to start to stall.

I can't seem to reproduce it however.

I feel something else is still wrong considering the gauge and the voltage readout. I want to make sure I am not stranded on a road somewhere because of it.

 

[budwich]

OK... so not sure what you were thinking that you were testing with "So I decided to run positive lead on my multimeter to the cig lighter, and negative to a purple wire on the obd connector and it comes up saying 13.1v..."....

Putting your red meter lead "anywhere" and then putting your black lead "anywhere" may or may not be "checking" anything that is "explainable". "Normal" testing for voltage is done by putting the red lead on the "test point" and the black lead on a KNOWN ground.... unless you are testing for a voltage DROP across a given "element" which then could be any voltage value depending on what else is in the DC circuit.

 

[my98nnj]

Your voltage reading indicate nothing is wrong.
You came up with a bad battery and replace it.
The "problem" has now gone away.

Leave the truck alone, go grab a beer and enjoy the weekend.