Suspicion of a bad Engine Ground

Status
Not open for further replies.
Originally Posted by cjcride
Glad it's fixed. I would put a little battery grease or vaseline on the clamps/post and you're set for years.


I did that as well as the felt 'washers' that came with the new terminal ends. I would rather have replaced the entire cable than just the ends but the weather was not cooperative. Maybe once it warms up I can replace them all.
 
I just replaced all of my battery, charge, starter, and ground cables with 4/0 anaconda welding cable. Also ditched my twin Group 65 batteries for two Group 31 units. First time I started up after doing that, I thought I broke something it cranked so fast.
 
Ok, scratch that, something is still not right.

The car started and ran fine this morning. Drove all the way to work fine (16 miles) in the cold with the heater fan and headlights on the whole time. Started up fine and drove around the block a bit around lunch time, ran fine. Started up this afternoon to head home and ran fine then as well. I started it again this evening to go get gas and a few things from the store. It started fine and ran well, noticed on the way to the gas station that the interior lights seemed a little dim. Started okay leaving the gas station, drove to the store and headlights and dash lights were very dim. Just for giggles I shut the car off upon arriving at the store and went to re-start it and it was very slow/clicky to start. After I came out from the store it started okay but then the lights went dim to the point of almost being off by the time I got home.

By the time I pulledin the driveway my instrument cluster had stopped working and some 'idiot' lights were on. What do I check next?
 
Alternator output. Charge that battery up using a proper battery charger, and then measure voltage with the engine running. If you don't have better than 14 volts, your alternator let your last battery drop dead and now is letting your new battery drop dead while driving.

I dealt with this exact situation on a friend's car just last week. She had Bad battery, replaced, car still died, I checked voltage and the alternator was shot. Now good after a new alternator feeding her new battery.

Worth noting that this was a 7 year old Acura and gave zero warnings that the alternator had failed. Guess they don't care about voltage that much.
 
Last edited:
Originally Posted by DoubleWasp
Alternator output. Charge that battery up using a proper battery charger, and then measure voltage with the engine running. If you don't have better than 14 volts, your alternator killed tour last battery and now is letting your new battery drop dead while driving.

I dealt with this exact situation on a friend's car just last week. She had Bad battery, replaced, car still died, I checked voltage and the alternator was shot. Now food after a new alternator feeding her new battery.

Worth noting that this was a 7 year old Acura and gave zero warnings that the alternator had failed. Guess they don't care about voltage that much.


I did a test just now. Sitting voltage with the key off was about 13.7. I watched the multimeter while attempting to crank the car over and it only clicked and flashed lights, but voltage didn't go below 12v.

I should mention also that I have an exhaust leak near the back of the motor (where the starter and alternator are). Could this be a heat soak issue? Even if it was, I don't know that it would cause the lights to dim while I'm driving...
 
I think your meter might be 1 volt high if that was truly with the key off. Car running should be 13.5v or more and static battery voltage (koeo) 12.6. Under a load it should not be below 10.5-11v

Check your battery connections and grounds again to be sure you have proper connections.
 
Last edited:
Ok, I went back out and checked, static voltage with the car sitting, key off was at 13.45v I tried the key and it cranked slow but started. Now it's showing under 12v at the battery while running, I tested the alternator itself while the engine was running and the numbers flipped between 10v - 11v and would jump up to 18v. It's hard to tell as I'm using a digital multimeter.
 
The voltage regulator is bad if it's going from 10-18v. If it's pcm controlled there may be an issue with the wiring or the pcm. What kind of vehicle is this again?
 
Originally Posted by mattd
The voltage regulator is bad if it's going from 10-18v. If it's pcm controlled there may be an issue with the wiring or the pcm. What kind of vehicle is this again?


2001 Ford Focus Zetec 2.0 DOHC
 
Also, I went back out to re-check the voltage drop from the pos battery terminal to the big terminal on the back of the alternator was something like 10.9 - 11v... that doesn't make sense. I checked the negative battery terminal to the alternator casing and it showed 2v. Due to my curiosity I checked the battery post to the end of the new engine ground I'd added, also showed right around 2v. Then from the battery post to the battery terminal, also showed 2v.

I touched the two terminals on the multitester together and it reads 2v.... is this an indication that the tester is bad? I feel like I'm getting nowhere.
 
Yes your tester is bad. Make sure you are set to DC volts (the 20 volt range for most car testing).

WIth the leads shorted together or opened the voltage should read zero.

If with a good meter you find a substantial voltage between the big output wire on the alternator and battery (+), there is a break in the circuit. In some cars (mostly Japanese) this wire goes through a big fuse. Other designs (mostly American) use a fusible link wire. But it is always intended to be constantly connected even with the key off. This is why you must disconnect the battery before trying to R&R the alternator, if you short the wire to ground something will burn out.
 
Last edited:
Originally Posted by mk378
Yes your tester is bad. Make sure you are set to DC volts (the 20 volt range for most car testing).

WIth the leads shorted together or opened the voltage should read zero.

If with a good meter you find a substantial voltage between the big output wire on the alternator and battery (+), there is a break in the circuit. In some cars (mostly Japanese) this wire goes through a big fuse. Other designs (mostly American) use a fusible link wire. But it is always intended to be constantly connected even with the key off. This is why you must disconnect the battery before trying to R&R the alternator, if you short the wire to ground something will burn out.


I found another meter, a good one, and it now shows 11.45v static, measured from +Bat to +Alt, once I scratched thru surface corrosion, got less than .1v difference, solid 0.0v on -Bat to -Alt. Just to be sure, I checked -Bat to +Alt and showed 11.45v.
 
Originally Posted by DoubleWasp
And the voltage with the engine running at idle?


I will check this again when I get home. Working a half day today, had to take wife's car.

Oddly enough, jumped the Focus this morning and it started okay and ran long enough to get it out of the driveway, move the Mountaineer out and then get it back in. Headlights and fan on and nothing dimmed or died. It's almost like the alternator situation is an intermittent thing.
 
Originally Posted by DoubleWasp
And the voltage with the engine running at idle?


I came home from work, tested the cold battery at 11.8v. Tried it and it cranked over a bit slow but started. Idle voltage is 14.7, started turning on accessories and can't get it lower than 13.5v. I have the high beams, blower fan, rear defrost all on and its still at a steady 14.5v. It did dip down into the 12s when I first unstuck the power windows. Also dipped into the 11's on a re-start attempt.

Where do I go from here? it tests out perfectly and I can't think of anything different about last night's trip other than it was more stop and go than my normal commute was. I had lights on all the way to work and they don't seem to be drawing an excessive amount of power.
 
Left it run for about 5 minutes with full accessory load. Went back out and it's running but showing 11.5v. Shut off and restart several times and the voltage shows right around 11.5v, same measuring at the alternator.

Does this mean the alternator only works when it's cold?
 
Originally Posted by OVERKILL
Definitely sounds like the alternator isn't charging at this point. Could very well be heat-related.

Alternator is cool to the touch but I can't come up with any other explanations
 
Originally Posted by OVERKILL
Definitely sounds like the alternator isn't charging at this point. Could very well be heat-related.

+1
 
Well I've run aground yet again as the back/lower alternator mounting bolt head is rounded off. It is/was a 10mm, I've tried tapping a socket on and even a smaller 3/8" socket to no avail.

EDIT. I am now trying to get the pigtail plug disconnected in hopes that maybe there's some heat related connection issues going on there.
 
Last edited:
Status
Not open for further replies.
Back
Top