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Engine Specific Info and Questions => IDI Engine => Topic started by: Heron on December 29, 2016, 04:18:33 pm
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Sorry, 4th thread on this truck but I was advised to start new threads..
Trying to figure this starter situation out from another thread but this is a whole new issue:
I've got a disconnect on the ground of my battery in the truck to disconnect at night as to avoid any electrical fires in my garage.
I've had this issue before the disconnect and tested the battery with the neg cable attached to the end of the disconnect and it works as expected.
So, I go to test my solenoid wire and find when I test the lead directly to the top of the negative terminal with the disconnect on(chasis and tranny ground not working) I get a full 12v with key on
But, when I turn off the disconnect and allow it to ground to the transmission and chasis the voltage drops to .05V, same thing on my glow plug circuit.
If I test the battery by itself and test with the ground at the battery or at either the transmission or chasis it tests the same as the ground at the battery. (grounds good)
Summary:
Starter is not in and starter cable not attached to anything(other than hot going back to fuse box)
1. Battery tests good at all locations including disconnect and two grounds; transm and chasis
2. Solenoid wire tests at 12v if I connect ground lead directly to battery terminal but if I turn disconnect off(allowing tranny and chasis to ground) and check it then at any location, terminal,disconnect, chasis/tranny cable then I get .05 Volts at not only solenoid wire but also glow plug strip... ???
3. If I put the ground lead on battery terminal, ground to tranny and chasis off(disconnect on), test the solenoid wire I get 10v with key off, key on ,I get 12volts
4. If I put ground lead on battery post with ground to terminal with disconnect on(chasis and tranny ground not connected) on and I touch engine, transmission etc...I get minimal voltage readings as if the tranny and motor are energized.
Is this a ground issue perhaps behind the fuse box or some other type of short(relay, ign switch)?
I feel it is more than likely a ignition switch...could be the cause of my exciter wire/charging light staying on. Something positive has shorted to ground. I have removed the plug from alternator
Could it have something to do with my glow plug relay? I've read about that shorting and causing all kinds of issues(truck starts immediately. virtually no delay with no cold start advance)
Just tested the 3 prong alternator wire(it has two reds and a blue):
All 3 had 12 volts! I'm not thinking the blue wire should be 12v...correct?
I then removed the fusible link to the alternator and now there is no more weird voltage on the engine, transmission but there is also no voltage at all on the solenoid wire when the key is off, on or the start position...the starter is still not hooked up.
I apologize for the madness...took me 5x to get this straight on here..I thought this would be an easy project :o
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So, I go to test my solenoid wire and find when I test the lead directly to the top of the negative terminal with the disconnect on(chasis and tranny ground not working) I get a full 12v with key on
But, when I turn off the disconnect and allow it to ground to the transmission and chasis the voltage drops to .05V, same thing on my glow plug circuit.
If I test the battery by itself and test with the ground at the battery or at either the transmission or chasis it tests the same as the ground at the battery.
This is consistent with the alternator exciter wire being shorted. Voltage drop through a diode is around .5V.
It might not be the only problem, but you gotta start somewhere and you know the exciter wire needs to be addressed. I'd pull it out of the cluster connector or just clip it close enough to splice new wire to it.
At this stage, I'd pull out the fusebox (it should just have a dozen big connectors on the back)... if the fusebox looks swollen, it may have gotten wet and corroded inside. Having the fusebox out will also give you a good view of the wiring to check for damage from mice, water, or professional mechanics.
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Is there any trick to fusebox removal? Is it covered well in the Bentley?
I may start with the alternator plug side b/c when I unplugged the hot from the battery to the alternator(at the fusible link) all of the points like the head stopped testing for voltage. So, something having to do with that particular wire has a bearing on the situation...i think. ::)
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Not well covered in the Bentley, I'm afraid...
If you can post a pic of the fusebox, that might help. It's been a few years since I had my caddy and I don't know/remember if it was a westy.
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Not well covered in the Bentley, I'm afraid...
If you can post a pic of the fusebox, that might help. It's been a few years since I had my caddy and I don't know/remember if it was a westy.
Fuse box was one screw, worked it out of the tabs. Rats nest of wires but no corrosion or damage except 18 guage wire from what looks like the horn that needs some attention.
Okay, redid this post since earlier today:
Checked all wires, no issues from fusebox to alternator.
As I said earlier I have a Motorola alternator with one plug; two reds one blue exciter.
When all is hooked up except alternator plug I test with ground probe on ground of battery but battery ground not hooked to chasis or tranny=
Pos side of tester on anything, block, strut towers= No voltage readings
When all is hooked up and I plug up alternator plug and check the exact same way as above I now have voltage everywhere, block, strut tower, tranny...
Even though Autozone said the alternator is good I'm thinking I must have a short in the alternator transferring voltage to alternator housing and the rest of the block, tranny etc...
Now, if I hook up the chasis, tranny ground to the battery and then with ground side of probe on battery terminal and test the block, head, tranny I get some quick spikes of volts.. Thoughts on internal short on the alternator... ??? ??? ???
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Sure, it could be a shorted diode pack.
I would first test the blue (exciter wire) to make sure it's not shorting to ground: With the key on (engine not running), the light should be illuminated when the alternator plug is in, when the alternator plug is out, the indicator lamp should not illuminated. With the key off, there should be no voltage at the blue wire, with the key on there should be voltage, slightly less than the battery voltage.
I would test that the alternator case is grounded to engine>chassis>battery (neg).
I would make some 10ga jumper wires with spade terminals to go between the plug and the alternator, then with the red wires jumpered between the plug and the alternator, I'd run the engine and momentarily jumper 12v to the field terminal (where the blue wire connects) rev the engine like usual and meter the output red wires... no voltage means bad alternator.
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The charging light would not go off originally. Between starter issues and charging lt not going off started me down this road.
There is and has never been a ground strap on this alternator..and there were never issues.
If the diode pack can short that must be what it is. The two red wires stay hot but should not tranfer voltage to the alternator shell. Hence all is fine when its not plugged up but as soon as its plugged in the alternator along with the engine and tranny test for vo!tage and the vo!tage goes right into the exciter wire when its plugged in along with the two red wires.
Am I on the right track?
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The tests I described above in post #5 are pretty conclusive, if performed.
Metering the chassis/block/alternator case should show voltage, since there are connections from the positive to electrics in the vehicle like the clock/radio/etc. that have connection to ground. I get the same results on my 86 Jetta.
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The tests I described above in post #5 are pretty conclusive, if performed.
Metering the chassis/block/alternator case should show voltage, since there are connections from the positive to electrics in the vehicle like the clock/radio/etc. that have connection to ground. I get the same results on my 86 Jetta.
I will run the tests, my starter has been giving me issues..not sure if that is part of the issue.
Couple of questions before I run the other tests:
If the key is off, two red wires plugged to alternator and I test the blue wire(cut right now) coming out of the plug that is attached to the alternator I have 9-10volts. With exciter wire disconnected from alternator there is no light on the dash like there was before.
With the all three wires plugged up I now have voltage everywhere and on the solenoid wire with the key off
Yet, if I disconnect blue wire, I have no voltage at the solenoid wire with key off-- starter works perfectly..no spinning and clunking.
So, should the blue wire coming out from the plugged in-plug have voltage with the key off?
Is this voltage backfeeding into the cluster and such causing starter issues and exciter light to be on?
Thx much for the help!
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This voltage on the blue wire sounds all wrong. I was under the impression that the exciter wire was only providing voltage when the alternator is running. Not with the key off.
Sure sounds like something is fouled up with the blue wire. Shorted to ground from mouse chewing?
This makes me want to pull out the voltmeter and go pop the hood on my 81 for you but the sun just set and I would only have 15 mins of daylight left. Not enough to really get started as I don't have a garage space to work in. Maybe tomorrow if it is sunny.
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Sure, it could be a shorted diode pack.
I would first test the blue (exciter wire) to make sure it's not shorting to ground: With the key on (engine not running), the light should be illuminated when the alternator plug is in, when the alternator plug is out, the indicator lamp should not illuminated. With the key off, there should be no voltage at the blue wire, with the key on there should be voltage, slightly less than the battery voltage.
I would test that the alternator case is grounded to engine>chassis>battery (neg).
I would make some 10ga jumper wires with spade terminals to go between the plug and the alternator, then with the red wires jumpered between the plug and the alternator, I'd run the engine and momentarily jumper 12v to the field terminal (where the blue wire connects) rev the engine like usual and meter the output red wires... no voltage means bad alternator.
Exciter wire:
Alternator plugged up, key on , light illuminated
Unplug it, key on and no light
Key on: 11.3 volts at the exciter wire, grounded terminal on neg battery post
Key off: No volts at exciter wire
Resistance measured at alternator .13...Ground okay
No charging when running with light illuminated and engine revving.
Jumper 12v from battery to exciter wire at plug and now CHARGING!
So, just under 12 volts like you said on the exciter wire with key on but how would less then one volt make a difference?
Next step?
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This voltage on the blue wire sounds all wrong. I was under the impression that the exciter wire was only providing voltage when the alternator is running. Not with the key off.
Sure sounds like something is fouled up with the blue wire. Shorted to ground from mouse chewing?
This makes me want to pull out the voltmeter and go pop the hood on my 81 for you but the sun just set and I would only have 15 mins of daylight left. Not enough to really get started as I don't have a garage space to work in. Maybe tomorrow if it is sunny.
Checked the exciter wire all the way thru and looks perfect. If you look at the above post I did what Tyler suggested and found I had just less than 12 v with the key on. I was checking it before without the battery grounded to the tranny and chasis. I was getting volt readings all over the motor and all but Tyler had said that was normal. So, when I rechecked with all grounds connected to the batter and my tester on the post I got different readings.. ??? I like auto electric about as much as plumbing, although since I've done more plumbing it sure is easier. ::)
Now I'm really confused.
Alternator is good but my exciter wire is not carrying enough voltage with the key on to trip the field. But all the connections look good where the blue wire connects into the cluster. I even tightened up the 7mm screws on the back of the cluster that I read someone had luck with that.
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Next step?
I would add my black jumper cable from the alternator case to the neg post on the battery along with the normal cables. If the charging system and alternator light work properly, the ground path back to the battery is suspect.
Typically, I use a 2ga neg battery cable directly to a bolt holding the tranny to the block.
If the car was kept in a coastal region, the salt in the air can cause corrosion everywhere.
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At the risk of not being very helpful. Recently, after the car had been sitting a couple of weeks while getting an injection pump and fueling issue sorted out, the charging light wouldn't go off when i revving the the trucks engine. Nothing had been changed with the electrical system except the ignition switch had been replaced several months before without any new and/or associated problems cropping up. It took about 3 miles of driving before the light went off, something it had never done before and hasn't done since. The truck already had the alternator case grounded to the battery directly (like the starter). i might have missed it but am not sure if you have been able to take the car for a short drive?
These cars do strange and un-explainable things; it can get a bit crazy. May be put the light issue on the back burner, relax and watch a game or two, till you can drive it around the block a couple three times?
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Now I'm really confused.
Alternator is good but my exciter wire is not carrying enough voltage with the key on to trip the field.
The blue wire is notorious for internal breaks near the alternator.
Voltage is just one aspect, the wire has to carry enough current... a wire with some broken strands might show voltage on a meter but not carry enough current to do the job.
With the key off, there should be no voltage at the blue wire or the D+ terminal on the alternator where it connects.
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At the risk of not being very helpful. Recently, after the car had been sitting a couple of weeks while getting an injection pump and fueling issue sorted out, the charging light wouldn't go off when i revving the the trucks engine. Nothing had been changed with the electrical system except the ignition switch had been replaced several months before without any new and/or associated problems cropping up. It took about 3 miles of driving before the light went off, something it had never done before and hasn't done since. The truck already had the alternator case grounded to the battery directly (like the starter). i might have missed it but am not sure if you have been able to take the car for a short drive?
These cars do strange and un-explainable things; it can get a bit crazy. May be put the light issue on the back burner, relax and watch a game or two, till you can drive it around the block a couple three times?
The truck is no near roadworthy yet. I would drive it and see if possible. Before I picked up the truck from my father's house he had said there were no lights on in the dash. The truck has not been run for more than 15 min since then. I was not running it until I switched out the timing belt.
I'm trying to get the basics in check and work from there but you advice is appreciated. B
I'm going to start by running a jumper ground as Tyler suggested. I'm also going to check voltage at the radio fuse as I read somewhere that fuse controls the guage cluster.
If that doesn't work I'll snip the exciter wire close to the cluster and run a brand new wire.
I'd feel better if there were like 2 or 3 volts at the exciter wire but the fact there are 11.3 volts and it's not enough to trip the field...argh..although like Tyler said it may be current issue. Although wire looks perfect all the way thru, nothing butchered up under the dash.
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This voltage on the blue wire sounds all wrong. I was under the impression that the exciter wire was only providing voltage when the alternator is running. Not with the key off.
Sure sounds like something is fouled up with the blue wire. Shorted to ground from mouse chewing?
This makes me want to pull out the voltmeter and go pop the hood on my 81 for you but the sun just set and I would only have 15 mins of daylight left. Not enough to really get started as I don't have a garage space to work in. Maybe tomorrow if it is sunny.
OR Coaster:
The excitation voltage is there to get the alternator up and running in the start up stage. You could make an analogy with something like the pilot light on a gas stove. It gets the main burner going, but once the main is up and running, the pilot is no longer needed. Once the alternator output becomes equal to the battery voltage it becomes self exciting and the external excitation voltage is no longer needed.
Heron:
As I read it in the Bentley wiring schematic, current for that circuit comes off the number 15 buss (energized with key in 'on' position), goes through the warning light in the dash, and then out to the alternator, where you're getting 11.3 volts. The only thing in that circuit that would cause any voltage drop is the light bulb, and I have my doubts as to whether that little tiny light bulb would cause that much voltage drop. As you say with a wire jumpered directly from the battery you get the alternator to charge, so I'd say you have your problem isolated to that particular circuit. You did say that in the past you've had trouble with the warning lights in the dash. That might be an area to check. I've never had one of those apart but I suspect it's just a circuit card with a bunch of light bulbs soldered to it (or possibly LEDs, not sure if they had those back then). When those things go cattywhompus they can cause all sorts of electrical havoc. In addition to everything that Tyler has already mentioned that might be something to check into.
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Thanks for the analogy. Makes sense to me.
What is odd here is that the light comes and goes with the key as it should. But stays on when running. Which it should not. But yet the test of the alternator seems to have the needed output back to the battery which should shut the light off.
So is there something wrong with the voltage regulator in the alternator? There is nothing on the cluster that I can think of that controls much of anything. It is a piece of plastic with a film on the back that has thin printed circuit like lines that supply voltage to the sensors and light locations.
Could there be some crossing of voltage going on in that big white plug that inserts into the back of the cluster? Voltage for something like the temp sender being sent to the light on the dash making one think the alternator is not charging?
Gremlins are dancing on your hood here.
Get out the bells.
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In a way that little light on the dash does control the alternator. Since the excitation current runs through it, that circuit has to be intact for the alternator to even get started. As the alternator spins up and it's output level reaches the level of battery voltage, it becomes self exciting and shuts off the external excitation voltage(the blue wire). I can't say that I know exactly how it does that though, but anyway that's why you're warning light goes out when the alternator output comes up. Transversely.... if the alternator were going bad, and it's output level dropped below battery voltage, all that would be reversed and the warning light would come on. In this case, Heron in his troubleshooting has eliminated that circuit by running a wire directly from the battery to the excitation terminal on the alternator in it's place, and in so doing got the alternator to charge. This tells me the alternator and regulator are good, and somehow he's not getting enough current on that exciter wire to get the alternator up to proper output level.
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You pretty much got it...
The light goes on when it has 12V at the key/relay end of the circuit and near zero volts at the alternator... when the alternator is generating 12+ volts, the flow of current through the light (led) stops because both ends of the wire then see 12V. (no difference in potential, no flow)
So, why doesn't the wire excite the alternator, when a direct jumper does? Not enough current, voltage or both through the wire. Often strands are broken inside the insulation of the blue wire and it looks ok and meters ~12V... maybe there is resistance in the ground path and the combination of low voltage in the wire and resistance are keeping the coils from adequately generating magnetic fields.
It could also be something dragging down the system voltage, like a stuck/sticking GP relay... maybe in combination with the other factors. I know I need to rev my 86 Jetta faster by a couple hundred rpm to start charging during the post-glow period.
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Are the cables to the battery good? May be you posted about that already and i have missed it. i don't know why my charging light acted up awhile back and then fixed itself but...
i disconnected my negative battery cable today to check/replace my glowplugs. When reconnecting the battery cable the clamp broke in half; the red suffered the same fate in 2013. Likely it was already cracked. Since the problem goes away when you run a direct lead from the battery that made me wonder about the soundness of the clamps to your battery posts given that the cables on both vehicles are likely close to the same age. Easy to double check for cracks anyways. Sorry this whole thing is such a nightmare for you.
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SOLVED!
I did try grounding the alternator to the battery negative terminal. Did not help.
Basically I cut the exciter wire back at the battery area and tested it there. I had good voltage. I went forward to the alternator, tested it there and saw the drop.
Even though the wire looked good I cut it back right before it went into the the loom(what Tyler said) that travels under the radiator and spliced in a new wire.
Ran it a bit and now it is charging. ;D ;D ;D
Battery is up as I had it charging the entire time I was messing around with this issue but when the alternator kicks in if I have the lights on it drags the alternator down so much I have to idle it up but when the lights are shut down it idles up too much...probably another thread to start.. :-\
Thanks much for all of your help with this...Ask me what I did during my time off over the holidays and I'm still not done. ::)
Look for some more threads..I need to post some pics and get some advice on what to do with this truck.