I am posting this message in the chance that someone could potentially help my husband solve an issue with his classic 1970 Oldsmobile Delta 88. Recently the AMP light has come on in his dashboard. He has tried pretty much everything that he can possibly do to identify why the light is on. This has included the following:

Replaced Battery with a new one
Replaced Alternator with a new one
Replaced Voltage regulator with a new one
Replaced connector to Alternator
Replaced connector to Voltage Regulator
Replaced battery wire from Alternator to the battery
Replaced ground wires from the battery
Checked and replaced all the fuses with brand new fuses just in case
Replaced battery terminals on both positive and negative sides
Checked connection to the starter

Needless to say he is exhausted because the AMP light still comes on when the car is started and running.

Any ideas or suggestions would be wonderful! Thanks everyone!

 

I'm thinking it's the same as an A body. There is a brown wire that comes off the regulator (terminal 4) and feeds through the bulkhead connector and to the indicator lamp. It should have battery voltage on it when the car is running if the alternator is charging.

 

First thing I would check is if the replacement alternator is the correct externally regulated unit. If you have an internal regulator alternator on there plus the original external voltage regulator, it will create all kinds of havoc with your charging system.

Of course we all know parts counter jockeys would never give you the wrong part...

A good way to know is if he had to change the two-wire plug on the alternator from a plug like this I I to a plug lke this - - .

Past that, use the electrical troubleshooting section of the 1969 Chassis Service Manual. It will have a diagnosis chart for "ALT light on with engine running" . If you don't have a hardcopy you can find it on www.wildaboutcars.com .

 

Does the amp lite come on with the key in run position and car is not running?

 

Sorry, but THIS is why you should do some basic troubleshooting BEFORE throwing cubic dollars at a problem. First, about 3/4 of the items you've replaced have exactly nothing to do with the GEN light, so that money was completely wasted. The GEN light circuit is quite simple, and troubleshooting is described in detail in the Chassis Service Manual, which I would suggest getting before spending another dime.

The light on the dash gets +12V to one side of the filament when the key is on. The other side of the filament is connected to the field terminal of the regulator. That's the brown wire going to the regulator. This terminal on the regulator is grounded when the system is not charging and provides +12V when it is charging. When there is +12V on both sides of the lamp, it does not illuminate. The first thing to check is to see if you are getting +12V at the field terminal on the regulator. If you are, there is a problem in the brown wire from there to the lamp. If not, you still have a problem in alternator, regulator, or wiring in between. Since you've pretty much replaced everything else, my money is on the wiring.

 

While I don't have any diagnostic input to add, I'd just like to mention how nice I think it is, that you would post the question to help your husband. My wife only seems to want to place "for sale" ads in the classifieds.

 

I'm guessing there is no power to the light from the key side. There is no mention of a no charge condition, only a lite on when running. I would think if there is a lite and it is charging, there is an open circuit on the ignition side. Since the fuses have been changed, it may be an ign switch problem or the wiring to the bulb from that side.Possibly a connection in the socket or a broken printed circuit. I thought the lite wire went to #4 as it is set up on the reg as (F) 2 3 4 with 4 being the ign side from the light and F being field. Joe would you correct me if this is wrong? thanks.

 

From her post, it looks like he wouldn't ask for directions if he got lost, so let her be a heroine with the correct answer. It can be one of those (I told you so moments)

 

So, was it charging through all of this? Did you actually measure the voltage at the battery?

- Eric

 

If the circuit is open on the ignition side of the bulb, the GEN light will not come on. That wire would need to be grounded, with +12V coming from the regulator on the other wire, for the light to illuminate. If the wire is open, there is no path to ground and thus no complete circuit for the bulb to illuminate. This is not the problem.

 

Wouldn't the wire ground through the printed circuit from the ign side of the bulb if power was being generated back from the reg? If not why does the lite come on when the fuse is blown? If the alt is working and the fuse is blown the lite will come on when charging. Granted it won't come on with the key on and the engine not running. This assumes other circuits are being fed from the same feed as the gen lite on the printed circuit of course.

 

You are correct. Sorry about the mis-information. If the INST fuse blows (or is removed) the GEN light will ground through the filaments in the other warning lights and will come on when the car is charging. The +12V side of the bulb is powered by the same printed circuit trace as the other instruments. Of course, that means that the other instruments (like the fuel gage) will not be reading correctly. But, yes, it could be a break in the wire to the INST power pin on the printed circuit or a loose pin itself.

 

So we have multiple possibilities for the ladys problem. Most probable being a wiring problem or circuit problem. It looks like hubby will need to take some volt readings to narrow it down. I hope he bought a volt meter along with everything else he bought. Maybe then he can find the culprit. Like Eric said we still don't know anything of value with no test done. Hopefully hubby responds with volt meter in hand.

 

he could have bought a really nice multimeter for all of the money he spent on all that other stuff.

- Eric

 

X2 and have a spare and spare change.

 

Which bring up the question: Is the new alternator working correctly? I would verify this by having the parts store check it as we all know "new" doesn't always mean it actually works.

 

We also know even though a parts store checks it...

 

Yeah, maybe, but the times I had the parts store check alternators I was standing right there so I saw if it was working or not and not relying on the counter person to relay that info to me.

 

 

Is there a reason why you dredged up an 11 year old thread?

 

I had the same problem with my 70 delta 88. The previous owner had changed out the voltage regulator so I had eliminated it from suspicion. Regardless I bought another one and had it installed-no joy. My guy suggested to try another one so I bought another one and when he installed it, eureka!