I had a code 54 one time which would cause the car to cut out. The root problem ended up being a bad alternator which was on the way out. Low probability, but it did happen to me. I chased it until the alt died.
I had a code 54 one time which would cause the car to cut out. The root problem ended up being a bad alternator which was on the way out. Low probability, but it did happen to me. I chased it until the alt died.
electronics like proper voltage .. my flakey alternator in my truck keeps turning the ABS light on
I had a number of codes that appeared with a faulty O2 sensor. Only once did the O2 code pop up.Changed to a new sensors codes when away.
The point everyone is getting at, is that codes are a guideline for troubleshooting and may not be definitive.
Regards,
Miles
DD '87 Sundance T1, 12PSI, SLH with rear disks
'87 CSX #432
Hmm.... I never heard of some of these issues. The alternator isn't that old, though that doesn't mean anything. I did leave the map light on for a few hours before this issue started. I do notice the positive terminal of the battery is corroded. Maybe I'll clean the terminal, and read voltage while running to see what happens.Originally Posted by chromguy
If you have access to an oscilloscope, that would be ideal. You can take a reading right off of the alt.
What would the oscilloscope do that I can't read with a multi meter? If I put a volt meter on the battery terminals while its running, wouldn't I see a voltage drop if the alternator is acting up?
-Lee
Maybe. It's the real quick millisecond-range drops that are hard or impossible to see on a multimeter. An oscilloscope will show you a very obvious dip in the graph.
Jon J.
1989 Daytona ES 2.4L DOHC
2003 Neon SXT - gone but never forgotten
If it ain't broke, fix it 'till it is!
A oscilloscope can react very quickly to voltages changes and the multimeter is much slower to react. A multimeter is excellent for stable signals but a oscilloscope is specifically designed to analyze changing signals. For example, if the ECU is having issue controlling the alternator, a meter may not see the issue unless it is nearly dead.
https://en.wikipedia.org/wiki/Oscilloscope
Regards,
Miles
DD '87 Sundance T1, 12PSI, SLH with rear disks
'87 CSX #432
This is a nice handheld one, it is a dual trace unit. I made a pair of HEP test cables that can be used in between the HEP leads and the engine harness. If anyone has a dead HEP and can send me the plugs, I will put them in place of Ford wedgelock pins I used (they are the same OD as the HEP connector pins).
"growing old is inevitable, growing up is optional"
1986 Lebaron convertible to replace totalled 85
1986 Ford F350 Crew Cab DRW
1995 Lincoln Continental (project car)
2011 Ford Flex Limited (wife's)
Regards,
Miles
DD '87 Sundance T1, 12PSI, SLH with rear disks
'87 CSX #432
It was suggested to me that my alt might have been failing and a bad diode could have allowed a little AC current out of the alt which temporarily freaked out the computer. I'm not good enough to know, but I did buy a cheap scope after that.
https://www.seeedstudio.com/DSO-Quad...ope-p-736.html
Yes a faulty diode will do that
Regards,
Miles
DD '87 Sundance T1, 12PSI, SLH with rear disks
'87 CSX #432
Here is an interesting tidbit, AMC when they were still called Rambler, used a Motorola alternator which had a large pair of external diodes as a protection against failed internal diodes drawing the battery down. It also kept a bad internal diode from creating the telltale "whine" in the radio.
These were probably 60 amp or thereabouts alternators so it wasn't a real high current output.
"growing old is inevitable, growing up is optional"
1986 Lebaron convertible to replace totalled 85
1986 Ford F350 Crew Cab DRW
1995 Lincoln Continental (project car)
2011 Ford Flex Limited (wife's)
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