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99dgcummins

Need Help!! Electrical issue???

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99dgcummins

Ok guys my truck has me stumped! Ill start from the begining and tell everything... My truck was doing the TC Lock and unlock at 45 MPH, after reading some stuff online I tried wiggling the black and white wire going from the battery to the alternator, stopped that problem I would just have to wiggle it every 3 weeks or so. The WTSL wasnt coming on either. So one morning(Months Later)I was leaving and my truck would idle fine but when I put it in gear I would have to push the throttle down like half way to get it to go, the truck felt like it had no power, it went to 3000 RPMs before it would shift, and when it did shift it felt like it was going to die. I pulled over like 1/4 mile from the house and turned the truck off got out wiggled that black and white wire from the battery to the alternator it ran fine. Went back home let the truck sit and about 6-7 hours later started it up, took off, and it did it again. My check engine light came on, I put some de electrical grease in the plug on that wire and it stopped, it ran fine, CEL went off for about a week, and my WTSL came on for the first time in a year. I noticed that it does it almost every morning now so what I have to do is start the truck let it idle until it warms up turn it off get out unplug and plug in the plug in the wire going from the alternator to battery and it will run fine. Also the truck will not start until the WTSL comes on which is about 10 sec after I turn the key. Now that it is doing it again the CEL came back on so I took it to pep boys to have the codes read. The technician said that I have either a fuse blown or a short somewhere because the code reader wont pull the codes off the truck. Im stumped I dont have any idea what to do next!

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CUMMINSDIESELPWR

possible bad rectifier/regulator on the alternator causing bad power feed? just a thought, also check all grounds for corrosionecm problems?

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99dgcummins

I cleaned all the grounds as well as the battery terminals last week.

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MarbleCrusher

There should be a fuse for the DLC have you checked fuses?-Jordan-

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99dgcummins

I checked all the fuses in the fuse access inside and under the hood by the DS Battery all were good. I dont recall seeing one that was labeled DLC. Is it in the cab somewhere else or did I just miss it?Thanks, Corey

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Mopar1973Man

possible bad rectifier/regulator on the alternator causing bad power feed? just a thought, also check all grounds for corrosion ecm problems?

You can check diodes rather simply... Just use a DVM (Digital Volt Meter) and check the battery voltage while the engine is running on DC Volts. Then flip to AC Volts if it rises above 0.5 Volts you got a bad diode bleeding AC waveform.

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99dgcummins

Ok I have never used a DVM before, I went out and bought one and tested my batteries like you said. I am not sure if I did it right but when I put it on the batteries with the truck running I got; DCV-12.8-14.0, ACV-28.2-30.0. Did I do it right?

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Mopar1973Man

Ok I have never used a DVM before, I went out and bought one and tested my batteries like you said. I am not sure if I did it right but when I put it on the batteries with the truck running I got; DCV-12.8-14.0, ACV-28.2-30.0. Did I do it right?

Bad diode...:doh: Here is a quick video of that test...

http-~~-//youtu.be/UveGtGuswBw

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JAG1

99dgcummins, I read on TDR that you are supposed to cut that connector plug out of the wire from alt. to passenger battery and solder them together with shrink tube. Then also do the other one from Passenger battery that heads toward the firewall or PCM. Don't forget to unhook the batteries before doing this.BTW I used a straight butt connector, removed the outer plastic sleeve, crimped them together and soldered the whole thing in one. Shrink tube with the adhesive sealer is very important:thumbup2:

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Mopar1973Man

:wow:Hang on a second...Before chopping up any wiring just remember these truck ran 9-10 years without wiring mods and did just fine. So now all of a sudden require a bunch of hacking and cutting, adding grounds, etc... I don't thinks so.I still say to look for the issue at hand and not cover it up with a bunch of band-aids like adding grounds, filters, and tin foil... :duh:

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99dgcummins

Yeah I tested the batteries the same way shown in the video. I do believe it is my alternator because I am now seeing a big drop in voltage from my battery gauge in the truck while the truck is warming up and I believe the grid heater kicks in and out.(I read somewhere that the grid heater kicking in and out is the cause of the lights diming while the truck is warming.) When the lights dim the voltage drops almost to the bottom and when they brighten up it goes back to normal. This is all new so I am just going to get myself a new alternator... if the problem sticks around I will be back. Thank You guys for your help! Corey

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99dgcummins

Just bench test your current alternator before buying a new one... Save some money if you can!

Ok I will do that. Thank you for everything! Corey

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CUMMINSDIESELPWR

when my rig cycles the grid heater it may drop to about ~12v then go back up to 14.5 so i think your alternator is at the end. post up what u find after testing!

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JAG1

:wow: Hang on a second... Before chopping up any wiring just remember these truck ran 9-10 years without wiring mods and did just fine. So now all of a sudden require a bunch of hacking and cutting, adding grounds, etc... I don't thinks so. I still say to look for the issue at hand and not cover it up with a bunch of band-aids like adding grounds, filters, and tin foil... :duh:

Mike, a guy on TDR, Gary from Canyon City, Oregon found those two connectors have some issues with resistance. Maybe some don't but could be a step in the right direction for stopping future problems. The fact that the OP had to keep opening and closing one of them shows something was wrong there possibly. Do not want to give anyone a bum steer...:nono::tease:

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Mopar1973Man

Yeah it might be true that the ground connector gets weak and creates a issue... But still it would be better to fix the connector than remove it. Or protect it with di-electric grease from future problems.

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dripley

when my rig cycles the grid heater it may drop to about ~12v then go back up to 14.5 so i think your alternator is at the end. post up what u find after testing!

mine pulls down to 8 or 9volts. has since it was new. it is the same with new battteries and altenator. i have heard of others doing both like yours and mine. i am only saying this because there seems to be a wide spread an how far the grids will pull your gauge down.

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Mopar1973Man

mine pulls down to 8 or 9volts. has since it was new. it is the same with new battteries and altenator. i have heard of others doing both like yours and mine.

i am only saying this because there seems to be a wide spread an how far the grids will pull your gauge down.

Grid heater draw 195 Amps when functional... The alternator can only produce 120 Amps.. So there will be voltage drop and this is now based on how strong your batteries and condition of the battery cables. Any weakness in either will show with more voltage drop.

This is how I power my house with 820 Ah's worth of batteries weighing in at 1,000 pounds... (double ought Cables too!) So I got a really good understanding of batteries and loads... :smart:

Like since I'm 24V system here and the house has a max of 4,000w than means my max draw is 166 Amps... Grid heater consume 2,340w at 12 Volts... Anyway you slice it that is a huge amount of power being such from 2 smaller batteries and 1,440 watt alternator. :whistle:

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99dgcummins

UPDATE:I took my alternator off and took it to the parts store to have it tested. Guy said it was no good only puting out 7 amps, bought a new one installed it and the truck is still doing the same thing. While I was there I bought some electric cleaner and cleaned all the plugs to the alternator and the black and white plug going to the battery, also re-applied de-electric grease. What should I try next?My batteries are fairly new about a year old. Should I have them tested?

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Mopar1973Man

There should be a green and blue wire going to the field wire of the alternator. The blue wire should be hot 12V when the engine is running and the green wire should be a variable ground. Now the PCM is the voltage regulator so if the alternator is still not working right you might end up doing a old school regulator or changing out the PCM. http://mopar.mopar1973man.com/cummins/general/voltage-reg/voltage-reg.htm

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99dgcummins

Is there a way to test the PCM? I dont want to buy a new one if there isnt anything wrong with it. I know all signs point to it but after rent, bills, and diesel(my commute is about 140 Miles/day) so I dont have much at the end of the month.

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Mopar1973Man

The only way to be sure is get a hold of a dealer and have them drop there DRBIII tool on there and run a diagnostic on it. That will hurt for at least a shop hour at the dealer... (~$100)

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99dgcummins

So months later I am still having the problem. I finally decided to just take it to the Dealer. I've never taken a vehicle to the dealer so I am not sure if this is a normal thing but they wouldn't give me any codes, let me talk to the mechanic who ran the tests or anything. I had to deal with a middle man and all he would tell me is that I have a bad ECU. Does that sound right? I have tried to pull codes with a scanner and i got nothing so I am wondering if they are just saying it is the ECU because they couldn't get anything off of it. Them not letting me talk to the guy who ran the test made me suspicious. Should I be suspicious?

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