[Ramchargin82]

Hey Guys, RC just decided to leave me stranded (sorta). Was making a turn after driving for about 30 minutes and engine died. Coasted to a good stopping place, put it in park and go to turn it over and get a very weak crank. Just seems to me like the battery has been drained and since I wasn't giving it gas around the turn it just idled to low and died. Earlier this week I had a problem and a few of you thought it could be a solenoid...could this be the end result of something like that going bad? The alternator is fairly new with less than a year in service and not that many miles. Battery is also fairly new and I can't see any visual defects in the wiring. So, plan is to get my wife's pop to try to jump it (RC is about 6 miles from the house and he's about 2 from there) but I'm just wondering if I'll have the same problem if I stop giving it gas. Other options are either go buy a new battery to get it to the house or have it towed both cost about the same. Any ideas?

Thanks,
Bill

 

[Dodge 85 RC]

Yes that could be it. Other things to check are all connections to and from the battery and alternator.

 

[Ramchargin82]

The earlier problem stopped after jiggling around the battery connections. According to the guages I was getting charge just fine so I'm sorta stumped...what I wanna do is just get the thing back into my driveway so I can poke around at it...think if I get a jump I'd be able to limp it about 6 miles ok or safer to have it towed?

 

[Catsavvy]

Best way to start troubleshooting is by getting exact numbers.

Do you have a voltmeter? If you do not, I suggest very strongly that you get one. They are not expensive. Trying to fix an electrical problem without a voltmeter is futile. It can be done, if you have money to burn and replace parts using the "Shotgun" approach.

Check the battery voltage before you jumpstart the engine.
Jumpstart the engine. Check the battery voltage with engine running.

The battery voltage with engine running should be close to 14 Volts.

Let the battery charge up for at least 30 minutes. Keep monitoring with voltmeter. If you still are reading between 13 and 14 volts, drive the truck home with someone following you.

If you dont get the 13 volts, tell us what you find.

Start thinking about mounting a Voltmeter in the truck. And bypass the ammeter that you have.

If you had a voltmeter mounted, most likely you would'nt be in the fix you are in. You would have seen the early warning.

 

[macario]

Catsavvy, good advice about having a volt meter but what I always forget to do is to get readings when the RC is actually working right to compare to when it is not working right. Something to put on the list.

 

[Catsavvy]

Catsavvy, good advice about having a volt meter but what I always forget to do is to get readings when the RC is actually working right to compare to when it is not working right. Something to put on the list.

All cars, when working right, will have 13.6 volts at the battery when running. Thats how cars/trucks are designed.

A fully charged battery will be at 12.7 volts.

Not much to jot down . . .you either have your 13.6 volts, or you dont.
If the voltage is higher than 14 volts, regulator is overcharging.

If the voltage is lower than 13, with all accessories and lights off . . .the alternator is not putting out what it should. You need to troubleshoot with a voltmeter to find out the exact cause.

In my instrument panel, I mounted an Audi voltmeter that I got free at a junkyard. Now I know whats happening all the time.

 

[KThaxton]

Not much to jot down . . .you either have your 13.6 volts, or you dont.
If the voltage is higher than 14 volts, regulator is overcharging.

Just to add a little more info here....
The amount of voltage the regulator allows, is temperature dependend. If it is cold, it can be up to 15 volts.

 

[Ramchargin82]

Thanks for the info guys. I probably won't get to tracking this down til after Christmas, maybe wednesday while the munchkins are taking their nap since I'm off wednesday through the 4th. I ended up getting it towed (cost 40 bucks), but where it was sitting I needed to get it moved or I'm sure someone would have moved it for me. This is number one on my list to fix, then I'll get back on that heater problem. In any case, I appreciate the suggestions and I'll let you all know what the problem(s) end up being.

 

[skrat]

I am very courious to hear what the problem was with your RC because I have had the same problem with my '84. It will hold a charge with the engine off and it jump starts fine then runs for a while and eventually dies without enough juice to start. The alternator is good (had it tested) Replaced the VR and the batt is less then 6 months old. I am going to take the advice from earlier in this thread but if anyone has any other ideas that would that would be great.

 

[Catsavvy]

I am very courious to hear what the problem was with your RC because I have had the same problem with my '84. It will hold a charge with the engine off and it jump starts fine then runs for a while and eventually dies without enough juice to start. The alternator is good (had it tested) Replaced the VR and the batt is less then 6 months old. I am going to take the advice from earlier in this thread but if anyone has any other ideas that would that would be great.

The solution is in knowing how to use a voltmeter.
Measure and post your voltage readings at the:
alternator to ground
battery to ground
from alternator to battery
from battery neg to engine ground

 

[skrat]

OK catsavvy, I am posting what I got, but keep in mind that I'm an amature when it comes to most repairs and even more so when it comes to electrical. so there is a high probability that i did something wrong. that said here it is.

Alt to ground (wire going to frame by radiator) .4

ALT to ground (I am asuming that it is the green wire coming out of the ALT) .6

ALT to Batt. (assuming that is the bolt with the special plastic ins. on it) 1.0

I couldn't get the batt neg to engine ground wire off to put the tester inbetween B/c the nut was rounded off. pluss it seemed to be attached to the mounting bolt to what looks like the AC compressor. If that is crucial then might be able get irt off with vise grips.

I am not getting the 13.7 on the batt that I read somewhere that I should be getting if that helps.

Thanks in advance for any help you can give.

 

[DDGRC84]

sounds like you have a bad voltage regulator. my suggestion is to pull off one of the field wires (one of the two that just slide on) and jump it to a ground ( a ground is bare metal on the frame or block) then test voltage from the battery wire on the alternator to the engine block (ground). let us know what you get.

Jake

 

[skrat]

Thanks Jake, I will give that a try tomorrow.
I did replace the VR thinking that was the problem at first (about five people sugested that was probably it). could the new one be bad from the start?

thanks, Jerin

 

[DDGRC84]

you also may want to sand down the firewall and make sure that the VR is getting a good ground. going over what Catsavvy asked for, i noticed a slight discrepancy in what you gave us:

when you said alt to ground, you went from the battery wire on the alt (the one that screws on) to a frame or body ground?

when you said ALT to ground, you went from a field wire to ground. how about going from the positive terminal on the battery to a ground (engine block, frame, just make sure it is bare metal, painted or dirty metal will give you a bad reading)

and you did the alt to batt (from the battery wire on the alternator to the positive terminal on the battery) with the engine running, right?

 

[Smokey]

Jakes first line above may be the answer... SIMPLE STUFF FIRST.

GROUNDS ! Clean, sand to bare metal, and reattach the VR, do the same for the battery to block ground cable, make certain the block to firewall ground cable is clean and tight...

 

[Chump]

I couldn't get the batt neg to engine ground wire off to put the tester inbetween B/c the nut was rounded off. pluss it seemed to be attached to the mounting bolt to what looks like the AC compressor. If that is crucial then might be able get irt off with vise grips.

Take the bolt off with vice grips and get a new one and nut at your local auto parts store. The other end at the A/C compressor needs to be removed and cleaned/sanded also...they usually come from the factory with a big star washer under the cable end to ensure a good connection. It might just be wise to get a complete new cable? About $5 at Autozone. Clean the post off on the battery after you get the cable off.

 

[DDGRC84]

ideally on a vahicle you should have 6 grounding points. engine to body, engine to frame, body to frame, engine to batt, batt to frame, and batt to chassis. i think those were the right ones.

Jake

 

[83mcguyver]

ideally on a vahicle you should have 6 grounding points. engine to body, engine to frame, body to frame, engine to batt, batt to frame, and batt to chassis. i think those were the right ones.

Jake

There is one other thing I have found that is often a good troubleshooting tip... Check to see if there is any voltage difference (shouldn't be ANY) between the round post of the battery and the post lug at the end of the cable. Also a quick check to verify a good ground is check the voltage between the round ( - ) negative post and engine, alternator frame etc.
there shouldn't be ANY difference. Lastly, check the voltage between the ( + ) positive post on the battery (not the cable lug) and the battery lead on the alternator. There shouldn't be any voltage diffference if the cables are good and the battery connections are clean. IF there are voltage differences, check the cable lugs by measuring for any differences from the end
battery post lug to a point about 5 inches down the cable.
if you find ANY differences in voltage the cable may have a poor connection where it is crimped onto the post lug. I spent mega-bux trying to fix a intermittent problem when I finally found a bad crimp on the positive battery lug. The above are best measured with a digital meter, which are getting pretty cheap at parts stores. Remember that resistance (poor connection) + load (lights starter, winch, driving lights etc. equals heat! (think smoke and possibly fire). I hope this helps
someone as much as this bitter lesson helped me.

In case you are adding accessories, and forgot how to figure how much current something draws, so you can size the wire
correctly it's WATTS DIVIDED BY VOLTS = AMPS
i.e., a 100 watt driving light divided by 12.6 = about 8 amps.
I always use # 14 gage wire for accessory lights, and 16 gage
for smaller loads. Sorry, didn't mean to get off the subject.
-Rod

 

[skrat]

WOW! you guys rock! I am going go after all of that ASAP. I have to say that this site is the best Idea out there on the internet.

 

[theoldgoat]

Got to agree with Smokey and the others, that grounding, actually the lack of a good ground seems to be a major problem. My 81 RC did all manner of strange stuff untill I made up a good ground cable from the negative post to the body, to the block and then cleaned and scraped the area for good contact between the voltage regulator and ECU. One thing i also did in addition to cleaning and scaping the areas was to add "star" washers to help bite into the metal. Hope this all helps.