Re: Question: "low voltage at idle" deal
[Re: hemienvy]
#2714287
11/09/19 04:52 PM
11/09/19 04:52 PM
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Sniper
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Been reading a lot about this lately, there are several well known remedies.
My question is, does low voltage also keep the turn signal and hazard flashers from working properly ?
1979 D-150. I cannot figure out why the turn signals are so intermittant. Might act slower, but not intermittent. Related question: What do folks use to clean the contacts at plug-in points, male and female plug-ins ? Deoxit
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Re: Question: "low voltage at idle" deal
[Re: Mattax]
#2714462
11/10/19 10:17 AM
11/10/19 10:17 AM
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krautrock
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i rewired the alt output on my truck, (it's a 77 but i had the '79 wiring diagram), the bulkhead was bad, the connection going into it and feeding the electronics inside and the ammeter had alot of resistance. after rewiring, the turn signals did flash alot more consistent, also brighter and faster. wipers also work alot better, even at idle... i found this after i had rewired it, it's similar to what i did. https://ramchargercentral.com/electrical/ammeter-bypassbulkhead-fix/
Last edited by krautrock; 11/10/19 10:19 AM.
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Re: Question: "low voltage at idle" deal
[Re: krautrock]
#2714474
11/10/19 11:06 AM
11/10/19 11:06 AM
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Mattax
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The problem with that write up, and all the others like it, is that its based on a fundemental misunderstanding about power.
The 'full alternator power' NEVER flows through the ammeter. Power flows from the highest voltage source (usually the alternator) to the equipment, be it ignition, headlights, or whatever. The only alternator power through the ammeter is power needed for recharging.
The problems occur when the battery is run down a lot, then needs massive recharging; and more so when other stuff is attached to the battery side. Stuff like winches. It did not help that the ammeters on a several years of those trucks were in plastic housings. Running 40 ampos or more through those circuits was bound to heat stuff up. Then the pressed studs got loose.
But that doesn't change the fact that I began with. On a truck with no added accessories, power from the alternator does not flow through the ammeter, except what is needed to recharge the battery.
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Re: Question: "low voltage at idle" deal
[Re: hemienvy]
#2714548
11/10/19 02:45 PM
11/10/19 02:45 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
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Thanks Mattax !
I've been studying the heck out of the 1979 electrical schematics. When I first posted, I wasn't sure if the plug-in flasher units were voltage sensitive, the hazard and the turn signal units.
But now I have additional uncertainty about how the parking lights and the turn/hazard light system even works. I can't make sense of the circuits, the current flow. The schematic does not show the bulbs to be grounded, so where is the end of the circuit ? I don't have the full schematics - just the pages 2 through 5 that Krautrock posted in another thread. My guess is yes they are grounded. Maybe the socket is in direct contact with metal housing? As far as voltage sensitivity - indirectly yes they are. The flasher units have a metal or bi-metal strip the current flow through. The current heats up the strip, and it bends or snaps away from the contact breaking the circuit until it cools again. Current drawn by any bulb is voltage dependent. Lets take an 1157 bulb's brighter filment as an example. It's rated to draw 2.1 amps at 12.8 Volts. When provided power at high voltage, say 14.5 Volts, it will draw more current. It will also burn hotter and brighter. Yes - Give it too much voltage and it will burn itself out kindof like a fuse. The catch is that the bulbs must see that higher voltage to draw more current. Even when the alternator is producing power at 14.5 Volts, resistance in the connections leading to the turn signal circuit will reduce the voltage to some extent. I'll look at the diagrams I do have and see if it the turn signal and parking light circuits look similar to the set up in my '67 Barracuda or '85 Grand? Wagoneer
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Re: Question: "low voltage at idle" deal
[Re: hemienvy]
#2714596
11/10/19 06:24 PM
11/10/19 06:24 PM
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Joined: Jan 2003
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Related question: What do folks use to clean the contacts at plug-in points, male and female plug-ins ?
I disassemble each connector from the harness one at a time, by pushing in on the locking barbs with a jewelers screwdriver, and once out I use a dremel with a wire brush attachment to scrub them clean.Then I bend the locking barbs back into position, use some dielectric grease on the connector and snap it back into place in it's respective place in the harness.
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Re: Question: "low voltage at idle" deal
[Re: hemienvy]
#2714696
11/11/19 01:49 AM
11/11/19 01:49 AM
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Dave_J
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Hemienvy, where in Washington might you be? I am fair at electrical issues. I live in 'Little Detroit of the West".
I just rewired my sons 1974 D200's under hood due to so many corroded connectors. On Ebay you can get new Bulkhead male and female connectors that lock in the bulkheads plastic. His 10 gauge alternator feed to the Amp meter was bad and the return to the battery was totally melted and not charging the battery. His headlight wires were 18 gauge, not the 16 gauge as in the wiring diagram. They are now 14 gauge.
Retired, US ARMY 1973-1994 ASE mechanic, Electrical 1994-1997 Retired GTE/VERIZON/FRONTIER 1997-2015
Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.
03 Suzuki Burgman 650(Burger King) Scooter 65 Formula S Cuda 78 Little Red Express Truck 98 Buick Regal (wifes car)
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Re: Question: "low voltage at idle" deal
[Re: Mattax]
#2714738
11/11/19 10:32 AM
11/11/19 10:32 AM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
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I don't have the full schematics - just the pages 2 through 5 that Krautrock posted in another thread. My guess is yes they are grounded. Maybe the socket is in direct contact with metal housing?
I forgot where I got that schematic, I saved it to my computer. I see now, that little mymopar.com tag on the bottom though, just poked through that site and found it... link to download the pdf... http://www.mymopar.com/downloads/79_Dodge_Truck_Wiring_Diagram.zipedit: link to the page with the schematics. http://www.mymopar.com/index.php?pid=24
Last edited by krautrock; 11/11/19 10:33 AM.
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Re: Question: "low voltage at idle" deal
[Re: hemienvy]
#2714833
11/11/19 03:09 PM
11/11/19 03:09 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
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Burdar I put in new flasher dealies for both turn signals and hazard. I can swap the two units and still I have turn signals but no hazard. Right now the turn signals won't turn off after a turn, so I want to replace the turn switch anyway. I haven't searched yet for that, I would prefer to find an NOS piece if possible but maybe they are now unobtanium.
Dan Stern (Daniel Stern Lighting Consultancy) had some but not sure if they are the correct ones for your truck. He posts on FABO and Slant Six forums but you could just look up his website for contact info. Looking at the full size pdf for the '79 truck, The turn signal flasher gets power from the run circuit. J10A feeds the fuse. The fuse in turn feeds the flasher via the short connector (F11A) Hazzard is fed from F38 (prple with white) which comes direct from the battery. So check that for power into the fuse. The hazzard fuse connects to the flasher via F40 (pink). Check that next.
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