Charging Issue

[refugeefromcalif]

I've searched around here and can't find an answer to my problem.
My alternator stopped charging and the oil pressure gauge is pegging at 12 o'clock? Both started their problem at the same time.
I installed the DMCH Motorola 140A alternator about 2 years ago. All wiring still looks OK, (And I've checked for loose wires).
I've also played with the bulkhead connectors, (unplugged and plugged back in), to see if it made any difference. Nope.

I've added a short video of my gauge cluster to show what's happening on start up.


https://www.youtube.com/watch?v=Hz0hQx9qc48&feature=youtu.be

Any ideas of where else I can start looking with my meter?

George

[David T]

You have 2 separate problems. The alternator is not charging and something is wrong with your oil pressure gauge *maybe*. With the OEM sender that is normal behavior. The very first thing is to have your battery tested. If it checks out, check the wiring and the belt on the alternator. If it all looks good your alternator needs to be pulled and bench-tested.

[hmcelraft]

Have you disconnected the oil pressure sending wire - by the oil filter - to see if anything happens?

[refugeefromcalif]

You have 2 separate problems. The alternator is not charging and something is wrong with your oil pressure gauge *maybe*. With the OEM sender that is normal behavior. The very first thing is to have your battery tested. If it checks out, check the wiring and the belt on the alternator. If it all looks good your alternator needs to be pulled and bench-tested.

I don't know how old the battery is. I got the car from DMCF almost 3 years ago and the battery doesn't have a date code on it. The wiring and belt for the alternator look good to the eye.
I do have a new oil sender unit but, have avoided installing it as the OEM one was still working fine. I'll have the battery and 2 year old alternator bench tested.


Have you disconnected the oil pressure sending wire - by the oil filter - to see if anything happens?

Not yet. Once it stops raining I'll try that.

George

[Jonathan]

If you say the two problems started at the same time, then it could be coincidentally two separate problems, but more than likely they are related.

If they are caused by the same thing, then it likely stems from something they have in common. The bulkhead connector is a good start, as they are right beside each other in the WHITE connector on pins 30 and 31. If that didn't get bumped, and you already had it out and it looks ok, maybe something on the inside got bumped (or chewed)?

Check the oil pressure sender (gauge) wire at the engine as mentioned. It is right near the alternator so possible something happened there that affected both systems.

Less likely but possible is a common short or problem in the instrument cluster. I assume you would have mentioned if you had the cluster out recently? Those two go to the same main middle connector, but don't share much else other than being near each other on the printed board. Since your low engine oil pressure light goes on and off as it should, I would not think it's the actual oil pressure and that it's only the gauge sender that's a problem and not the warning light sender.

My vote would be for something having been bumped back at the engine, like if you had your oil changed recently or something and when replacing the oil filter, the long end of a filter wrench got tangled up in the alternator and sender wiring.

EDIT: post a photo of the passenger side of the engine, down low from underneath showing the oil sender, filter and alternator if you could.

[DMC-81]

There is something that I wondered about when I installed my alternator. The unit (especially the plastic part in the back) is very close to the exhaust manifold. I feared that over time the heat would affect it. Just a theory. Has anyone had a heat related failure or melting? I currently have heat shielding on the 6 brown wires.

35519

[Ron]

I've added a short video of my gauge cluster to show what's happening on start up.


Any ideas of where else I can start looking with my meter?$.02

IF the battery sits all night w/o a charger being on it and has enough power to crank the engine by itself, the odds are it is OK. Since the light is blinking, the connection to the alternator is probably OK too. So, if the output terminal (brown wires) has a good connection back to the battery, it is probably the alternator...Seams the light continuing to blink after startup indicates this too.

[refugeefromcalif]

I was finally able to do some more checking today on the alternator.
Using my volt meter I determined that the volt gauge is reading correctly. (Battery voltage only when running).
With a closer visual inspection I saw Little bits around the front of the alternator.

I still have my original Motorola 90 but, I upgraded for a reason so, I'm going to call DMCMW tomorrow and get a Motorola 120 on the way to me.

(Why/when did the Motorola 140 offering become a 120)???

George

[Bitsyncmaster]

(Why/when did the Motorola 140 offering become a 120)??? George

I just installed one. The dyno sheet that came with it still says 140 amp but at 2,500 engine RPM it says 135 amps. So I guess some people complained it was not a 140 amp alternator.