73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Electrical => Topic started by: 1979ChevyMorgan on December 25, 2015, 12:27:19 am
-
Hello everyone and let me start off by saying merry Christmas. So about a month ago i replace most of the gaskets and fluids in my truck (1976 Chevy Cheyenne 3/4 4x4 454) and then when I go to start her the thermostat gasket decided it needed to rupture (poor quality gasket or ripped im not sure) so it sprayed coolant everywhere. I shut the truck off and clean up as best as I can. Then I go home for about 2 weeks on leave from the Navy and come back put a better thermostat gasket on and go to turn the key and it acts like a dead battery, weird because I disconnected the cables before I left. My dummy gauge reads about 8 volts. So i take my multi meter to the battery and it reads 13. I think its a shortage somewhere but im terrible with electronics and my chiliton has no wiring diagram in it. Thought some coolant may have gotten onto the starter wires but I havent checked the current down there yet. I was just wondering if any of you guys could point me in the direction of some wires to check that im assuming the coolant hit and mucked it up or something. Truck will spin but its just like a dead battery. Starter engages and spins about oneish turns and thats it. Any help would be appreciated! Would really love to get my baby back to the dirt roads where she belongs!
-
Batt can read 13 volts but not have enough Amps.
Have the batt tested.
You could try to jump start it.
-
I had it jumped and replaced it with 2 other batteries I had. Still same result.
-
You've got a large resistance in the cables.
A voltage drop test will tell you where it it.
-
I don't believe that the antifreeze fuild would have a shorting effect in the wiring unless you have a relay or switch in the starter circuit; after all the engine compartment is always exposed to water, sleet and snow one time or another. If you have already tried a good fully charged battery with the same results, it's possible something in the starter circuit is shorted out. Things to check in that circuit are the starter solenoid or ignition switch. You can get a wired button starter switch which connects the starter solenoid's positive and negative post and you then push the button to turn over the engine. If is starts right up, you may have a faulty ignition starter switch. If it doesn't start, you may have a faulty starter solenoid. You can purchase a new starter solenoid online pretty cheap and be careful because the solenoid may have reserved power in it.The only other thing to test is the continuity (or ohm test) of the wiring from the bulk connector's starter connection to the starter and battery. Do your research when doing any repair that you never done. Hope this helps out and Merry Christmas.
-
If your battery is good and you cleaned the terminals, hook jumper cables from your battery to a good engine ground and the starter solenoid. If it starts, you have bad connections or bad battery cables. If it still doesn't start, you most likely have a bad starter. Look at the small wire from the battery negative to the fender. If it's melted, the main ground is bad, and the starter is trying to ground through it and overheating it.
-
If your battery is good and you cleaned the terminals, hook jumper cables from your battery to a good engine ground and the starter solenoid. If it starts, you have bad connections or bad battery cables. If it still doesn't start, you most likely have a bad starter. Look at the small wire from the battery negative to the fender. If it's melted, the main ground is bad, and the starter is trying to ground through it and overheating it.
Easier than that.
Take a digital multimeter set on > 20vdc range.
Read battery voltage should be > 12.3vdc.
Touch one probe to the battery ground and the other to the block. If it reads > 0.1 volts there's a questionable connection.
Touch a probe to the positive battery post and the other to the starter BAT stud. Again... If it reads > 0.1 volts there's a questionable connection.
Sent from my SM-P605V using Tapatalk
-
Alright so to give an update, ive been busy with work so I havent had much time to look at her. Tested the starter turned out to be a bad starter (really bad) so i replaced it and the solenoid. Hooked it up and still getting the same issue. Im getting 13ish volts to the starter and solenoid traced the wires up to the altenator and im getting 13 there too. Took the multi meter and ran it from positive on battery to a ground on the body and it also reads 13. Hooked up some cables to the positive to that same ground i tested before and it put my dash gauge at about 9 or 10. Raised it alittle but not really much. So this means it must be an ignition issue right? Does anyone have a good wiring diagram of that? ive looked on google and havent found much. Thank you guys for your responses.
-
Did you remove the intake manifold to replace the gaskets?
The official GM factory 1976 CK Wiring Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_76_1976_GM_Light_Truck_Wiring_CK_10_30_Only.pdf), courtesy of hatzie.
Pay close attention and, with the help of a trusted assistant, do the following steps exactly as outlined - don't shortcut. Firmly set the park brake, shift the transmission into park or neutral, and be very careful of rotating belts, pulleys and ring gear while cranking. Take steps that the vehicle cannot move:
- Connect your voltmeter across the positive and negative cable connections to the battery and record the voltage reading while your assistant attempts to crank the engine.
- Connect the voltmeter negative probe to the battery negative post and the voltmeter positive probe to a patch of clean, bare metal on the starter motor case. Record the voltage reading while your assistant attempts to crank the engine.
- Connect the voltmeter negative probe to the battery negative post and the voltmeter positive probe to the starter solenoid small "S" terminal. Record the voltage while your assistant attempts to crank the engine.
- Connect the voltmeter positive probe to the battery positive post and the voltmeter negative probe to the 3/8" battery cable stud on the starter solenoid. Record the voltage reading while your assistant attempts to crank the engine.
- Post the results of your measurements, tying the measurements to steps 1 - 4.
-
Did you remove the intake manifold to replace the gaskets?
The official GM factory 1976 CK Wiring Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_76_1976_GM_Light_Truck_Wiring_CK_10_30_Only.pdf), courtesy of hatzie.
Pay close attention and, with the help of a trusted assistant, do the following steps exactly as outlined - don't shortcut. Firmly set the park brake, shift the transmission into park or neutral, and be very careful of rotating belts, pulleys and ring gear while cranking. Take steps that the vehicle cannot move:
- Connect your voltmeter across the positive and negative cable connections to the battery and record the voltage reading while your assistant attempts to crank the engine.
- Connect the voltmeter negative probe to the battery negative post and the voltmeter positive probe to a patch of clean, bare metal on the starter motor case. Record the voltage reading while your assistant attempts to crank the engine.
- Connect the voltmeter negative probe to the battery negative post and the voltmeter positive probe to the starter solenoid small "S" terminal. Record the voltage while your assistant attempts to crank the engine.
- Connect the voltmeter positive probe to the battery positive post and the voltmeter negative probe to the 3/8" battery cable stud on the starter solenoid. Record the voltage reading while your assistant attempts to crank the engine.
- Post the results of your measurements, tying the measurements to steps 1 - 4.
I'll try that as soon as I can get an able body and a better multimeter. Mine just crapped out on me yesterday. And yes I did replace the intake gaskets.
-
... yes I did replace the intake gaskets.
Pay particular attention that the battery ground cable connection to the engine is clean and tight through all of its various brackets and bolts.
-
OK, so here's what I've got so far. Connected the multimeter from negative post to negative cable. And it reads 12.8 so something is grounded out I think right? Traced it so far to the power cable from solenoid up to I think the cable that goes threw the firewall. Red power cable that comes down and then splits to the alternator. It's not the alternator because I unplugged it's wires and still had the same result on meter. Ground cable to engine is good. Bat terminals clean and cables good. I'm pretty new at electrical work so I'm fairly lost at this point. Haven't had the chance yet to do your test "bd".
-
Correction, it's not the one going to firewall. I'll post a video here in a sec
-
Guy was also telling me something about a neutral safety switch? Can't seem to find it though. Looked up under the dash by steering column.
-
...Connected the multimeter from negative post to negative cable. And it reads 12.8....
Post more about this.
Are you saying you disconnected the ground cable and inserted the meter between the battery and cable? Or, did you connect the meter between battery negative and the ground cable with the cable attached to the battery? Was anything ON at the time, such as the dome light, engine compartment light, starter, etc?
-
Yes, I disconnected the cable from the battery and have the meter hooked up to the negative terminal and then to the negative cable with the positive still hooked up to the battery. To my knowledge there is nothing on. I really at a stand still at the moment, i have weird hours so it will be hard for me to do that test and i can only work on her a few hours a day. Im also ran out of ideas. Next time I have some daylight Ill try and post a video or something maybe that will be better descriptive. Because im sure it has to be something easy, its a 76 afterall. No computer or anything. Before it sprayed fluid ran just fine after it sat for awhile this problem happened so im faily positive that should have something to do with it unless by mere chance they happened at the same time. (when I say spray I mean spray, like all the way up to the windshield)
-
Inserting a voltmeter in series with a circuit is a "bad test" that will only serve to mislead you. Don't do it!
[Here's why: A decent digital voltmeter with an input impedance (sensitivity) of 10 megohms will indicate 12.8 volts with only 1.3 ľa of current flowing through the meter. In other words, an insignificantly negligible, parasitic current flow will cause the meter to register full system voltage. What you are actually doing is measuring the voltage drop across the meter itself. It is a meaningless, useless measurement that has no bearing on what you are trying to accomplish with a meter].
Perform the tests that I previously outlined, with no deviation, and you will make headway.
-
Inserting a voltmeter in series with a circuit is a "bad test" that will only serve to mislead you. Don't do it!
[Here's why: A decent digital voltmeter with an input impedance (sensitivity) of 10 megohms will indicate 12.8 volts with only 1.3 ľa of current flowing through the meter. In other words, an insignificantly negligible, parasitic current flow will cause the meter to register full system voltage. What you are actually doing is measuring the voltage drop across the meter itself. It is a meaningless, useless measurement that has no bearing on what you are trying to accomplish with a meter].
Perform the tests that I previously outlined, with no deviation, and you will make headway.
Roger that, as soon as I can get someone to help me out ill see to it. And post results
-
Ok so i know its been awhile. But BD i still havent been able to get anyone to help with the truck and my multi meter is broken. So itll be alittle bit before I can work her. I did how ever put a push button start in there. One wire down to the soleniod on the switch terminal and one to the battery. I did put a fuseable link in there too. And that still doesnt work. Also reads 17.4 volts now with or without the push button start. My brother said something about maybe a bad battery cell or something? But that still wouldnt explain why it wont be jump started either or would it?
-
When a battery has a bad cell if will typically read about 10.5 volts, a bad cell produces no voltage or little voltage. A good, fully charged battery should have around 12.6 to 12.8 volts at the terminals. Now, you replaced the starter, so if the battery is good (have it checked at the parts store) then I would check for power at the fuse block (ign) and also check the voltage drop there. However, you wires in a push button directly to the solenoid which rules out ignition. So, test the battery, if it's good, clean the terminals real good with baking soda and water, clean the cables as well, make sure they are tight, check your grounds, then make sure you hooked up the new starter correctly (and makes sure it's connections there are clean) then see what it does. Wiring in a remote start switch (the button) eliminates everything but battery, cables, and starter. So it's one of those 3, honestly it sounds like a bad battery, but may be cables. Btw, I have seen several bad batteries that wouldn't jump either, I've used jump boxes directly to cables disconnected from battery to jump cars before...it's not the best way, but in some cases it's the only way, after all a jump box is a battery.