OBD1 Codes

[Tiha]

UPDATE today I checked the battery all is ok, checked the alternator (fully disconnected from all sources) the DVOM reads 1069 VAC, is this borderline bad/good? I will continue to check the VSS cable for any ruptures kinks etc... I have not driven the truck as of all this.
Lou

How did you check the alternator?

If you unhook the alternator, put a test light between the large battery wire and were the wire attaches on the alternator. If the test light lights up you have a bad diode in the alternator.

But usually that will drain the battery in a couple days.

 

[Basque1]

have you ever pulled the cover and looked at the teeth?

Maybe it didn't apply to the 8" rear ends. But I was thinking there was a TSB that said, pull the cover and check the teeth on the reluctor wheel.

Granted I have never seen a damaged one in person, but seen pictures.

Faulty alternator is possible. Unhook it and go for a drive. Alternator can put AC voltage into the system is there is a bad diode and I believe the VSS as a sign wave.

Checked the diodes of the alternator and this was the reading 1069 VAC. I have not taken the diff cover off.

 

[Basque1]

How did you check the alternator?

If you unhook the alternator, put a test light between the large battery wire and were the wire attaches on the alternator. If the test light lights up you have a bad diode in the alternator.

But usually that will drain the battery in a couple days.

Used a digital multi-meter 1070 VAC fully disconnected, I also did a full test of the battery and alternator load etc and that came out normal in the 14+ volts range.
.

 

[Motech]

Oh wow this is weird, one question if I do have a faulty alternator, wouldn’t it be affecting my tach reading. I do remember that happening in my Cobra the alternator went and my tach was very erratic which lead me to change the alternator.

Not necessarily. It depends on the type of tach signal, analog vs digital. If it is digital, RFI will not affect it at all.

 

[Motech]

checked the alternator (fully disconnected from all sources) the DVOM reads 1069 VAC, is this borderline bad/good?

If that's 1069 mVAC, that's borderline and can cause issues at higher engine speeds.

If that's really 1069 VAC, that's insane nan!

 

[Basque1]

If that's 1069 mVAC, that's borderline and can cause issues at higher engine speeds.

If that's really 1069 VAC, that's insane nan!

Humm, I thought it was borderline, are you implying that the diodes are goner? And this is the most probable cause of my sudden problems?

 

[Motech]

Humm, I thought it was borderline, are you implying that the diodes are goner? And this is the most probable cause of my sudden problems?

I just looked at your photo - didn't catch that before.

You've got that set on diode testing, which tests for diode integrity and polarity. I'm not even certain what that 1070 value represents.

To test for AC voltage, hook it back up across battery terminals and set your meter to the ACV 200 setting up top in red. (That's a pretty high range, but if it is a leaky alternator, you should see something)

Take your measurements with alternator fully enabled and charging, and rev up your engine to 3000 RPM.

With industry standards of 50-100 mV AC max (that's .05 to .1 volt), you shouldn't see jack in that meter range if it's good.

Anything above 100 mV AC can cause disruptive RFI on sensitive circuits.

In your case though, I'd expect to record some peak AC Voltage above .5, maybe even above 1.0 at high engine speeds.

Basically, if you record any AC Voltage at all in your meter, disable your alternator and try it again.

 

[Basque1]

I just looked at your photo - didn't catch that before.

You've got that set on diode testing, which tests for diode integrity and polarity. I'm not even certain what that 1070 value represents.

To test for AC voltage, hook it back up across battery terminals and set your meter to the ACV 200 setting up top in red. (That's a pretty high range, but if it is a leaky alternator, you should see something)

Take your measurements with alternator fully enabled and charging, and rev up your engine to 3000 RPM.

With industry standards of 50-100 mV AC max (that's .05 to .1 volt), you shouldn't see jack in that meter range if it's good.

Anything above 100 mV AC can cause disruptive RFI on sensitive circuits.

In your case though, I'd expect to record some peak AC Voltage above .5, maybe even above 1.0 at high engine speeds.

Basically, if you record any AC Voltage at all in your meter, disable your alternator and try it again.

Ok I will try that method. I unhooked the alt and tested it for diode integrity by putting the red tester on the alt casing which gave me that reading and the black on the output post. When I inverted that test I got no reading. But I will get back to w when I redo what you are telling me, Tks buddy.
Lou

 

[Basque1]

I just looked at your photo - didn't catch that before.

You've got that set on diode testing, which tests for diode integrity and polarity. I'm not even certain what that 1070 value represents.

To test for AC voltage, hook it back up across battery terminals and set your meter to the ACV 200 setting up top in red. (That's a pretty high range, but if it is a leaky alternator, you should see something)

Take your measurements with alternator fully enabled and charging, and rev up your engine to 3000 RPM.

With industry standards of 50-100 mV AC max (that's .05 to .1 volt), you shouldn't see jack in that meter range if it's good.

Anything above 100 mV AC can cause disruptive RFI on sensitive circuits.

In your case though, I'd expect to record some peak AC Voltage above .5, maybe even above 1.0 at high engine speeds.

Basically, if you record any AC Voltage at all in your meter, disable your alternator and try it again.

Ok here are the results I placed the digital meter on ACV at 200 scale as you told me . At 1000 rpms the reading was 31.9. I Accelerated to 3000 rpms and the reason was 31.8. I am assuming based on your previous statement that these readings are below 50-100 mVAC that this is within range? Yes / No ?
Tks Lou
PS
I did not take a reading with the alternator disconnected as I did yesterday.

 

[L\Bronco]

Ok here are the results I placed the digital meter on ACV at 200 scale as you told me . At 1000 rpms the reading was 31.9. I Accelerated to 3000 rpms and the reason was 31.8. I am assuming based on your previous statement that these readings are below 50-100 mVAC that this is within range? Yes / No ? Tks Lou I did not take a reading with the alternator disconnected as I did yesterday.

Not familiar with your meter, but the lowest range is 200V A\C, it is unlikely that a scale this high can read in millivolts. If it does, it will say "mv" wherever the range indicator is on the screen. Yours doesn't appear to have that feature. That means your reading is likely 31.8V A\C. I've never seen one that high.
If you followed Motechs instructions to the letter, I would replace that alternator.
I have had them with 2 of the 6 diodes open showing 1-2 V A\C before. but never 30!
Maybe try and find a meter to borrow with a much lower scale Mv would be best.
Can you remove it and have it tested at a parts store? (O'riellys)
That would take out the maybe's.
Hope that helps
Cheers

 

[Basque1]

Not familiar with your meter, but the lowest range is 200V A\C, it is unlikely that a scale this high can read in millivolts. If it does, it will say "mv" wherever the range indicator is on the screen. Yours doesn't appear to have that feature. That means your reading is likely 31.8V A\C. I've never seen one that high.
If you followed Motechs instructions to the letter, I would replace that alternator.
I have had them with 2 of the 6 diodes open showing 1-2 V A\C before. but never 30!
Maybe try and find a meter to borrow with a much lower scale Mv would be best.
Can you remove it and have it tested at a parts store? (O'riellys)
That would take out the maybe's.
Hope that helps
Cheers

Well I don't know what else to do all my results are wacked out and I am hesitant to buy anything until I can pin point the culprit. I don't have an O'Reilly b y me and the Autozone and Advance Auto parts guys are as useless as screendoors in a submarine. Here is a picture of my digital meter.

 

[Basque1]

Here is my reading today as Motech asked me to do with the meter

 

[L\Bronco]

Here is my reading today as Motech asked me to do with the meter

Do the test again with the alternator disconnected and see what the meter reads. It should be very close to zero volts A\c with the alternator disconnected with the eng running.
Did you get a chance to look at the harness for the VSS?
Hope that helps
Cheers

 

[Basque1]

Do the test again with the alternator disconnected and see what the meter reads. It should be very close to zero volts A\c with the alternator disconnected with the eng running.
Did you get a chance to look at the harness for the VSS?
Hope that helps
Cheers

You mean the diode test? Red touching the alt casing and the black on the output post? With the digital tester on the diode test setting? I have not checked the VSS harness yet, bad weather here.

 

[L\Bronco]

You mean the diode test? Red touching the alt casing and the black on the output post? With the digital tester on the diode test setting? I have not checked the VSS harness yet, bad weather here.

Actually no, A\C meter on the battery as Motech instructed, eng running with the big wire off of the alternator. looking for 0 volts A\C (or as close to zero as you can get)

 

[Basque1]

Actually no, A\C meter on the battery as Motech instructed, eng running with the big wire off of the alternator. looking for 0 volts A\C (or as close to zero as you can get)

when you say the big wire there are 2 connections to the alt, the output stud and the side plug, both of them disconnected or just the bottom output stud?

 

[Motech]

when you say the big wire there are 2 connections to the alt, the output stud and the side plug, both of them disconnected or just the bottom output stud?

He means the output wire, the big one on the stud.

Or you can remove the belt. Or disconnect the regulator, the side plug. Either technique should disable charging and reduce/eliminate that AC voltage.

I've never seen AC RFI that high either, and if accurate, would surely be causing some serious electrical grief.

I am hesitant to buy anything until I can pin point the culprit.

I like that Basquel. That's my exact professional creed.

This is why I and @L\Bronco have each recommended driving it with alternator disabled as a confirmation.

 

[Basque1]

He means the output wire, the big one on the stud.

Or you can remove the belt. Or disconnect the regulator, the side plug. Either technique should disable charging and reduce/eliminate that AC voltage.

I've never seen AC RFI that high either, and if accurate, would surely be causing some serious electrical grief.



I like that Basquel. That's my exact professional creed.

This is why I and @L\Bronco have each recommended driving it with alternator disabled as a confirmation.

Ok I will try that once again and let you know

 

[Basque1]

Ok I will try that once again and let you know

Ok men Thursday 3-16-23, this is what I did, disconnected the wire from the stud of the alternator see picture
below. Turned the engine on and using the multimeter on the scale of ACV 750 the reading on the meter was 026 see attached picture of the reading.

<- reading engine on


after all these, I lifted the truck on my ramps from the rear to check the VSS wire harness, (my truck is spotless underneath being a garage king and all) and track the connection from the top of the diff, followed the wire loom (Looks oem by the way) all the way to the entrance to the truck frame and there are no kinks or evidence of broken wires.

HOWEVER, and I used caps for a reason, when I looked at the connector to the sensor noticed that the two snap legs of the connector we still semi open . This led me to believe that it was not fully plugged in!! I pushed it in and sure enough it clicked and now it appears to be all the way in.
I took the car fro a road test and drove it slowing until reaching 50MPH no blinking over drive light. Increased the speed to 65mph no OD blinking light, I drove it for about 14 miles total and suddenly it flashed the OD light for a few seconds but it went away. At no time there was harsh shifting or limp mode. I think I am on to some progress??? What I will do now is pull the VSS connecting lug again and ensure that it is clean and I will put some dielectric grease into the plug and test drive it again. Your thoughts guys.
I seem that the alternator is not the issue YES/NO?

UPDATE- 2:15 PM
Removed the VSS plug again cleaned well and added the the dielectric grease. plugged back in again ensuring that it is nice and snug, drove it for about 40 miles in total at different speeds, with and without the cruise control and tested the OD functionality and all id peachy so far no glitches no flashing OD light. The truck seems more responsive all in all I think it is fixed . Your tghoughts and comments are welcomed and tks for your patience.

 

[L\Bronco]

Ok men Thursday 3-16-23, this is what I did, disconnected the wire from the stud of the alternator see picture
below. Turned the engine on and using the multimeter on the scale of ACV 750 the reading on the meter was 026 see attached picture of the reading.

View attachment 31084<- reading engine on


View attachment 31083 after all these, I lifted the truck on my ramps from the rear to check the VSS wire harness, (my truck is spotless underneath being a garage king and all) and track the connection from the top of the diff, followed the wire loom (Looks oem by the way) all the way to the entrance to the truck frame and there are no kinks or evidence of broken wires.

HOWEVER, and I used caps for a reason, when I looked at the connector to the sensor noticed that the two snap legs of the connector we still semi open . This led me to believe that it was not fully plugged in!! I pushed it in and sure enough it clicked and now it appears to be all the way in.
I took the car fro a road test and drove it slowing until reaching 50MPH no blinking over drive light. Increased the speed to 65mph no OD blinking light, I drove it for about 14 miles total and suddenly it flashed the OD light for a few seconds but it went away. At no time there was harsh shifting or limp mode. I think I am on to some progress??? What I will do now is pull the VSS connecting lug again and ensure that it is clean and I will put some dielectric grease into the plug and test drive it again. Your thoughts guys.
I seem that the alternator is not the issue YES/NO?

Congrats, I would say, definitely progress! Did you have the alternator reconnected during the road test?
Your voltage reading is still strange to me. (I am uncertain what "HV" on your meter stands for, plus you were on the 750 V A\C scale which makes your reading a full 26 volts A\C)
Something appears weird there for sure, but, I think its more meter related than anything.
I feel you are on the right track (providing the success isn't purely coincidental.) Clean up that VSS connector and try it again. If it still acts up, disconnect the Alternator wire and drive it, (If you haven't already done so.)
It doesn't look like the Alt is your problem, but its pretty easy to rule out.
Like I said earlier, there are a multitude of things that can make the light flash. But VSS is high on the list, so carry on the path you are on, (Till you hit a roadblock or fix it)
Good luck
Cheers!