Need Help With Wiring/Dead Draw Issue

[Tejasdge]

After a few months with no problems, my truck drained the batteries overnight again. I believe that the draw is a little above 10 amps, since it killed 2 multimeters that were 10 amp max. I also held fuses across the terminal and post and blew a 5 amp, but not a 15. Being a "Southern" engineer at heart, I then formulated the spark method. I methodically disconnected wires and pulled fuses and circuit breakers until there was no sparks when I brushed the negative terminal against the post. I would highly recommend that you NOT use the spark method, since I may have smoked the electronics, but I was on a mission.



I have, so far, traced the draw to the dark green wire with a white trace that is connected to a blue 18 gauge fusible link that is connected to the stud feeding the fuse box or, as they now call it, the integrated power module. This wire is directly connected to the battery, protected by the fusible link, and goes to the engine control module(ECM). I have not attempted to start the truck or read the codes since I have recharged the batteries to try to keep from resetting the problem for it to only reappear in another few days, weeks or months. Last time, I had the cooling fan speed code, which I can't recall the number just now, and replaced the electric clutch on the cooling fan. Then I revelled in my trouble shooting skills until late last week. :{



So here I am, looking for ideas, encouragement or any other form of divine wisdom. Maybe the name of a good auto electric shop in the greater Atlanta area.

 

[rbattelle]

I have, so far, traced the draw to the dark green wire with a white trace that is connected to a blue 18 gauge fusible link that is connected to the stud feeding the fuse box or, as they now call it, the integrated power module.

You need to find out what this circuit is. Maybe if you post a photo of where the wire is connected to this stud I can help locate it on the wiring diagram.



Ryan

 

[sag2]

If I understand your description correctly the circuit is the A140 off the PDC stud. There is an S166 splice on the A140 circuit but I can't find where it goes. The rest of the circuit feeds the ECM connector 2, pins 20, 30, 40. They are all DG/WT wires.

 

[Tejasdge]

If I understand your description correctly the circuit is the A140 off the PDC stud. There is an S166 splice on the A140 circuit but I can't find where it goes. The rest of the circuit feeds the ECM connector 2, pins 20, 30, 40. They are all DG/WT wires.

As usual, You are spot on. If it is spliced, that could be a good/bad thing. If not an ECM issue, good. Not knowing where the rest of the splice might go, bad. I need to look at the schematics a bit more to even make a wild guess.

 

[Tejasdge]

My head is spinning with wiring schematics, splice and connector locations, and green wires with white traces. I blew the 20 amp fuse on the new multimeter, so I need a burlier ammeter. Seems like no one carries the old, cheap, amp add-a-gauges anymore. I wonder if there is a generic shunt that will work with my multimeter once I replace the fuse?

 

[sag2]

First unplug the C2 connector on the ECM and try another fuse. I'll try looking at 2004 or 2005 diagram and see if the splice is the same and hopefully it will show where it goes.

 

[Tejasdge]

The schematic show the green/white being spliced, which I found, and going into the ECM. I have also found one going to the dash connector C130 and one into the PCM in C2. I guess the electrical engineers or manual writers figure that it's better to simplify the diagrams and spread it over hundreds of pages, but it's not very intuitive to me. That EE course is not giving me much of a rate of return.

 

[sag2]

OK, I think the S166 splice is just the fuse link to the A140 circuit. Cut the cover off the battery cable coming out of the fuse link to the ECM connector and find the S166 splice to see if there is another circuit coming off it. I just don't think there is. The same splice is there in 2004 and 2005 but no wiring takes off from it either. If it goes straight to the ECM C2, it is either shorted inside the harness to another wire, or the ECM has a problem staying powered up. Disconnecting the C2 connector should prove that out.

 

[KIKER]

Both my batteries in my '99 went all the way down in about 4 hrs one Sunday afternoon. I was in a panic to get it going for the job I had just gotten, so replaced the batteries first, alternator next and it was still showing about 6 volts on my gauge in the dash, so I knew I didn't have a chance to have found the problem. I disconnected the batteries to save them and when I did, it sparked quite a bit. I had it towed to the dealer and he found my air intake heater solenoid had stuck and was heating the grid constantly. He replaced the solenoid and grid and I was good to go 'til my lift pump went out 3 weeks later. The battery and alternator replacement is about the extent of my electrical ability, as far as elec problems go.

 

[Tejasdge]

I don't know how ya'll take this kind of thing, but when I can't fix something that I know I should be able to, it feels like I've had the wind sucked out of me. It just gets a bit too personal.



I got one of the new fangled clamp on testers for DC current and my drain vanished. Must of scared it away. I went ahead and started it up and was amazed that it ran after every connector on the truck had been taken apart. I am going to try to test the alternator in the morning by jumping the field. I have been told to supply 12v negative to one prong and positive to the other. I would appreciate confirmation, or the correct procedure. The voltage is fluctuating up to 15. 5 volts and jumping back down to the high 12's during the grid heater cycle. The odd thing is that the current seems to stay the same while the voltage changes.



I am also worried that the red top Optima's I have may be confusing the computer in some way. I will be loading up my old batteries as spares until I figure this one out.



Ahh, tomorrow is a new day.

 

[Tejasdge]

I hope that the problem has been found. The alternator tested out bad and the batteries good. I have a 220 amp replacement on the way. I will get the batteries tested again at that point to ensure they are ok. They about 2 year old Optima Red Tops. I have heard that the Optima's may have issues in our trucks. We'll see on Wednesday.