2nd Gen Non-Engine/Transmission Hunting a short... need some help

[SMcGrady]

I am trying to figure out where the short is that is causing my batteries to drain down. It used to take a couple of weeks of not driving the truck for my batteries to get so low that they wouldn't turn the engine over. It started getting worse so I replaced the batteries as they were the originals (13 years, 85k). Les Scwab also tested the system and said my alternator was bad, so I replaced it too... .

But, something is still draining the batteries in a couple of days... I had the batteries checked again to make sure I didn't get a dud, and they are testing good.



so... I got out my multi meter and started trying to track down the problem.



I am very embarassed to admit that I am not much of an electrician, and I don't even know very much about using this multi meter... So, I could use some help interpreting what I found.



With everything turned off in the truck, I set the multi meter to the 200m on the Amp selection and I pulled each fuse out, one at a time. I place the probes on each set of fuse conections. Nothing showed any amp draw until I pulled the "door locks" fuse. the meter read . 2 with everything at rest, then when I pushed the door lock button it went up to 27. 0.



Do you think the . 2 is evidence of a short? If so, is it enough to cause my problem? and if it is, any suggestions on where to look for a likely spot where I might find it?



Oh yeah, one other thing. the speaker in the passenger door cuts in & out when I hit a bump, so I know there must be a problem in that wiring or maybe the radio itself. Could this be related to my battery draw problem?



Thanks!

 

[JLandry]

The best way to check for a suspected parasitic draw like this is to disconnect the negative battery cables and connect your ammeter in series between one of the negative battery cables and its post. This will show you the total current draw of all parasitic loads. A very small current drain is normal for such things as the stereo memory, ECM, an alarm system, etc. , but they should all add up to a fraction of an amp.

If you are meauring more han an amp, then just as you did before, start pulling out one fuse at a time in both the PDC (Power Dist. Center) located under the hood, and the fuse panel on the driver's side of the instrument panel. If that doesn't turn up the source, then pull out the relays in the PDC one by one.

The usual culprits are the glove box lamp or the lamp under the hood getting stuck on.

Good luck,

John L.

 

[Crowhurst]

SBCM and IOD

On my quad cab the seat belt control module (SBCM), situated under the centre front seat, draws IIRC 100 ma for about 30 minutes after igntion off. This is to enable escape from the belts after, for example, an accident. If your vehicle has a SBCM, this can make your search for the underlying problem more complicated. I just wait the 30 minutes, watch the milliameter reading drop down, and then go fault-finding. You may know that the Ignition Off Draw (IOD) fuse can be pulled so that all currents which continue when the ignition is turned off are cancelled. This fuse position is marked IOD in the fuse panel. My apologies if you know all this, or it is not applicable to your truck.

Nick.

 

[SMcGrady]

Thanks for the replys! I tried what John L suggested first and disconnected the negs and checked for current. I got the same reading that I saw the other day on the pwr door lock fuse. (also checked the usual culprits you mentioned, with all checking out good. ) Then I pulled the IOD fuse that Nick mentioned. I checked all the fuses again, one at at time and got a . 2 reading again with the multimeter set up the way I discribed in my first post. (I don't know how many amps that reading means). I left that fuse out and rechecked the negative battery cable thing and the current draw was 0.

So, I think the short is in the pwr door lock circuit.



I have left that fuse out until I can take the time to trace the wires and ferret out the short. Does anyone see a problem with driving the truck around with that fuse out?



Finally, I checked for codes and found the following codes set. P1689, P0380, & P0382.

I cleared the codes after I charged up the batteries and pulled the Pwr door lock fuse. Then I drove around all day today. Rechecked the codes and no codes are set.

So far, so good...



So thanks again for the replys (and the help on the phone Ray). Please jump back in if anyone thinks I am missing something.

Scott-

 

[ghass]

As I see it the 200 m on your meter would be full scale 200 milliamps or . 2 amp (200 /1000) amp for full scale; (milli = 1/1000). So I interpret you reading . 2 as . 0002 amps, which is trivial, probably less than the error accuracy of the meter. Even 27 would be trivial, but the length of time the current is drawn by a solenoid to pull a lock is so short, that that reading is probably low (due to response time of the meter) but certainly not particularly significant.

The speakers cutting out are not themselves a problem, particularly if only momentarily on the vehicle in motion, but of course that could indicate other wiring has also lost insulation and is shorting, which can be an issue that you have not detected. I doubt this to be the case, as you would likely burn up the wire too.

What stood out the most is that you leave the truck standing for two weeks. You always have a little drain with the newer vehicles electronics. A fresh battery I am told loses about 1% per month if standing disconnected, and if not kept at full charge can detereate such that it never reaches full charge. This materially shortens battery life.

My suggestion would be to attach a float charger while you do not operate the vehicle. This device is a small charger, less than a trickle charger that keeps the battery to at least 12. 8 volts. I have been looking in to this and am told a full charge "12 volt" battery actually charges to as high a as 14. 2 volts and while charging to 14. 4 volts.
Keeping track of the voltage that your battery is delivering may provide a clue.

Watch it over time with the battery connected to the vehicle, then again disconnected. If you can, look at the specific gravity (must not be a sealed battery) of each cell to determine a shorted or bad cell. I just got a warranty adjustment on one that had one bad cell gravity but the store tester "passed" the test.

A cheap float charger is Harbor Freight item #42292 which goes for $5-$10, but only delivers 12. 8 volts. Not the best. I would look further. Do not leave a regular charger on continuously, as it can overcharge, unless you get a fancy multi stage charger. These chargers have equalization, charge, and float modes in them and have a higher price tag. Currently I have a charger permanently mounted in the truck and operate it a short time each day on a timer. I am considering that high price route, as I too have similar issues. With dual batteries in a diesel, annual equalization of the cells also makes some sense. That is another subject.

I am not an expert by any standards, but have had to deal with the issue from several viewpoints. What I know has been acquired in the school of hard knocks.

Hope this helps in some way.

 

[SMcGrady]

As I see it the 200 m on your meter would be full scale 200 milliamps or . 2 amp (200 /1000) amp for full scale; (milli = 1/1000). So I interpret you reading . 2 as . 0002 amps, which is trivial, probably less than the error accuracy of the meter. Even 27 would be trivial, but the length of time the current is drawn by a solenoid to pull a lock is so short, that that reading is probably low (due to response time of the meter) but certainly not particularly significant.



The speakers cutting out are not themselves a problem, particularly if only momentarily on the vehicle in motion, but of course that could indicate other wiring has also lost insulation and is shorting, which can be an issue that you have not detected. I doubt this to be the case, as you would likely burn up the wire too.



What stood out the most is that you leave the truck standing for two weeks. You always have a little drain with the newer vehicles electronics. A fresh battery I am told loses about 1% per month if standing disconnected, and if not kept at full charge can detereate such that it never reaches full charge. This materially shortens battery life.



My suggestion would be to attach a float charger while you do not operate the vehicle. This device is a small charger, less than a trickle charger that keeps the battery to at least 12. 8 volts. I have been looking in to this and am told a full charge "12 volt" battery actually charges to as high a as 14. 2 volts and while charging to 14. 4 volts.

Keeping track of the voltage that your battery is delivering may provide a clue.



Watch it over time with the battery connected to the vehicle, then again disconnected. If you can, look at the specific gravity (must not be a sealed battery) of each cell to determine a shorted or bad cell. I just got a warranty adjustment on one that had one bad cell gravity but the store tester "passed" the test.



A cheap float charger is Harbor Freight item #42292 which goes for $5-$10, but only delivers 12. 8 volts. Not the best. I would look further. Do not leave a regular charger on continuously, as it can overcharge, unless you get a fancy multi stage charger. These chargers have equalization, charge, and float modes in them and have a higher price tag. Currently I have a charger permanently mounted in the truck and operate it a short time each day on a timer. I am considering that high price route, as I too have similar issues. With dual batteries in a diesel, annual equalization of the cells also makes some sense. That is another subject.



I am not an expert by any standards, but have had to deal with the issue from several viewpoints. What I know has been acquired in the school of hard knocks.



Hope this helps in some way.

I have been thinking about adding some sort of charger to use when I dont drive the truck every day (usually just during snow events or when I am travelling abroad). I like your idea about the float charger... I need to do some more study of this... Thanks for the help. I am going to start by looking in the passenger door to see if I have some melted wires that intermittantly short out and might be causing my problems...

Thanks again.

Scott-

 

[SMcGrady]

So, I've been travelling for my job for the last couple of weeks and I had to let things set for a bit. Today I was able to do some more troubleshooting. Here is what I saw. I disconnected the neg side of the passenger side battery and put the multimeter in between the neg battery post and the end of the neg cable. I saw some current that went away when I pulled the IOD fuse. (Before I started, I pulled the bulb on the hood light, the glove box light, and had the button on the door pushed in so the interior lights were not on. ) Now, I never had the key in the ignition (for several hours in fact), but I noticed that when I pulled the IOD fuse and pushed it in I could hear a clicking sound from the driver's seat, near where the seat belt comes out. I could also feel the clicking in the seat back with my hand on the seat. So it makes me think that the seat belt controller should be unpowered as it has been much longer than 30 minutes since the last time the ignition was turned on/off... If that is correct, I would think that pulling or installing the IOD fuse shouldn't cause the seat belt controller to engage/disengage? Is this possible evidence of a failing seat belt controller module? Or am I chasing my tail again?

Thanks,

Scott-

 

[Nyoest]

The sound issue is prolly the speakers. I had the same problem and after a new set of kickers no more problems. I think it was the built in amps.

The charging problem is simple. Drive the truck.

 

[Crowhurst]

I'm abut 4,000 miles from my shop manual, but IIRC the 30 minute delay is to enable escape from the cab in the event of an accident, and the occupants being trapped because the ignition is off. I vaguely recollect that the system senses the opening of the doors, and the 30 minutes will reset again if the doors are opened. I therefore have the driver's side window down, the doors shut, and switch the ignition on and off through the open window. The shop manual has a complex test section for the SBCM, involving ignition on and off three times and then pushing in the cigar lighter to start a test routine. If you go to Advanced Search and search this particular forum for +seat +belt +control +module , and select posts, not threads, you will find much on this subject. The thread by Ncostello deals with just your symptoms, but without a result. Good luck.

Nick.

 

[HBarlow]

I agree with ghass above. Your ohmeter reading may be telling you nothing is wrong.

I wonder about the quality and condition of your batteries. When I read "Les Schwab" or other similar tire retailer in a paragraph about batteries and diagnosis of charging systems and also read that the tire salesmen told you your alternator was bad I am automatically suspicious. The employees of stores like that are commissioned salesmen whose goal is to sell product and service. I'm not saying they are all dishonest or incompetent but I would never let them diagnose my truck or sell me batteries and alternators.

It is odd but not impossible to hear of an alternator on a Dodge-Cummins that required replacement at 85k miles. I've never experienced it. I've had a couple of them freshened up with brushes and bushings at over 200k miles and continued using them. I've never purchased a new or rebuilt alternator.

You may simply have low quality batteries that don't hold a charge as well as the OEM batteries. I'd start with the basics. Have the batteries tested first.

 

[NIsaacs]

Here is what I saw. I disconnected the neg side of the passenger side battery and put the multimeter in between the neg battery post and the end of the neg cable.



Anytime you test for current draw, you need to dis-connect both neg. cables or the draw does not flow through the meter.



Nick

 

[SMcGrady]

I agree with ghass above. Your ohmeter reading may be telling you nothing is wrong.



I wonder about the quality and condition of your batteries. When I read "Les Schwab" or other similar tire retailer in a paragraph about batteries and diagnosis of charging systems and also read that the tire salesmen told you your alternator was bad I am automatically suspicious. The employees of stores like that are commissioned salesmen whose goal is to sell product and service. I'm not saying they are all dishonest or incompetent but I would never let them diagnose my truck or sell me batteries and alternators.



It is odd but not impossible to hear of an alternator on a Dodge-Cummins that required replacement at 85k miles. I've never experienced it. I've had a couple of them freshened up with brushes and bushings at over 200k miles and continued using them. I've never purchased a new or rebuilt alternator.



You may simply have low quality batteries that don't hold a charge as well as the OEM batteries. I'd start with the basics. Have the batteries tested first.

Thanks for the advice. I agree that a place that sells alternators and recommends a new one would be suspect. However Les Schwab does not sell or install alternators, and they have an good reputation in these parts for their batteries and other services.



I know it is quite early for my alternator to be having a problem, but it is not unheard of. I have had the batteries checked twice now since having the new one's installed and they check fine. I have started pulling the IOD fuse each night and no longer have the drawdown problem at all.



My last question is still unanswered though... It relates to how the seatbelt control clicks, with a vibration felt and heard in the backrest part of the seat, near where the seatbelt comes out, each time I pull the IOD fuse and agin when I reinstall it.



It does this even though I have not had the key in the ignition for hours, or days even...



I was wondering if this was an indication that the seatbelt control module is bad, as I thought that it remains powered for 30 minutes after the ignition is turned off... or is this just a dumb idea?



I have heard that the seatbelt modules have caused this problem before and I am not sure how to prove that it is or is not my problem.



Before I started pulling the IOD fuse each night, the drawdown problem had gotten worse and it only took 2 days to make my batteries go flat enough to not start the truck. I last drove the truck on Monday and I pulled the IOD fuse when I parked it. This morning I pushed in the IOD and my interior lights came on very bright and the truck started right up. Seems to be pointing to something in that circuit...

 

[SMcGrady]

Here is what I saw. I disconnected the neg side of the passenger side battery and put the multimeter in between the neg battery post and the end of the neg cable.



Anytime you test for current draw, you need to dis-connect both neg. cables or the draw does not flow through the meter.



Nick

Ah... Thanks Nick. I will try that when I get back in town... I am not very knowlegable about electical systems... unfortunately...