97 Deville Charging Issues

[waterzap]

Just bought a 97 Deville. Really great car. 42,000 miles, one owner. Clean history, car always serviced by Cadillac.

Also have a couple of older Cadillacs. 76 Seville, 78 Eldorado and 87 Coupe Deville. Member of Cadillac Lasalle Club, but I think with the newer car, this might be the place for advice. This car is a different animal. Took me 10 minutes to get the air filter box apart. With the 70’s cars can do it in the dark with my eyes closed.

The previous owners said that the car does not keep a charge. After a few days of standing the battery is dead. They tested the battery and alternator (so they say), and everything turned out fine.

The lights seem to dim slightly when driving at night, not applying any throttle. Also when I apply the brakes I can see a SLIGHT dimming of the lights. Just a tad dimming, then the lights brighten again. The display reads above 13, up to 14 or so volts while accelerating. No codes. Even under idle the display reads around 13 volts.

I just bought a new battery, and it does the same thing. I took the old battery in, and they said it looks fine, but only 26% charged. I drove around the whole weekend, probably 300 miles !!!!

If the alternator is bad, would the display still read over 13 volts? Anything else it could be? The belt / and / or pulleys also seem to be squeaking. Just ordered a new belt and idler pulley. Belt actually looks fine. If still squeaking will replace tensioner too. What is the torque specs for the pulleys? (will get factory manual soon).

I replaced the alternators on my other cars, easy as can be. Two bolts and thats it. With this one I really want to be sure its the alternator before I have to go in there. Dont even know where to start.

On a side note. The Dex Cool looked great. Oil life was good, only thing is the air filter was FILTHY. !! Don’t know if the dealer ever replaced that air filter.

[KHE]

Sounds like you have a parasitic drain in the system. If the alternator was not working, you would have a light on the dash.

Disconnect the negative battery terminal and connect an ammeter in series with the cable and the battery terminal. Open the trunk and hood. Wait for the system to go to sleep (after approximately 10 minutes). The amp drain should be less than 30mA (.03 amps). If it is not, begin pulling fuses until so see the ammeter fall below 30 mA. That will be the circuit that is causing the battery to drain.

If you have a trunk mounted CD changer, check to see that the magazine is not partially ejected. If that is the case, the CD changer will keep trying to eject the magazine and keep the PZM from going into sleep mode which will drain the battery.

[waterzap]

Will do, thanks.

Put the battery on a 2 amp charge last night, and it was still charging this morning. No CD changer in the trunk. See what looks like extra cables in the back. If I pick up a CD changer at the junkyard, wouldn't work?

Are all the radios the same?

[KHE]

Will do, thanks.

Put the battery on a 2 amp charge last night, and it was still charging this morning. No CD changer in the trunk. See what looks like extra cables in the back. If I pick up a CD changer at the junkyard, wouldn't work?

Are all the radios the same?

If the wiring is there for the CD changer, then it will work. You should have a SOURCE button on the radio control head which will toggle the input from the antenna, CD changer (if equipped) and the cassette player.

Not all the radios are the same.

[waterzap]

So I tested the draw last night. Not really anything there.

I got 0.005 A with everyting off. I then opened one door to see what happens, and the draw picked up a bit, but not much, up to 0.01 A

There is a terrible noise coming from the belt / and / or pulleys on the alternator side of the engine. Going to replace them all this weekend and see what happens.

Anyone know what the torque specs are for the idler pulley and the belt tensioner? I ordered the shop manual, but don’t have it yet.

Going to replace both plus the belt. If still a problem, guess will have to start measuring voltage drop.

Probably good idea to replace the pulley on the water pump side too, but that’s a job for another time.

Radio has a SOURCE button, so going to see if I can pick up a cheap CD changer this weekend!

[KHE]

The previous owners said that the car does not keep a charge. After a few days of standing the battery is dead. They tested the battery and alternator (so they say), and everything turned out fine.

I just bought a new battery, and it does the same thing. I took the old battery in, and they said it looks fine, but only 26% charged. I drove around the whole weekend, probably 300 miles !!!!

On a side note. The Dex Cool looked great. Oil life was good, only thing is the air filter was FILTHY. !! Don’t know if the dealer ever replaced that air filter.

Where are you having the batteries tested? Autozone? I have a feeling their tester always shows one of their batteries as good regardless of the condition. It "looked fine" but how could it be fine when it was only 26% charged? The battery needs to be fully charged, then the surface charge needs to be bled off, then a specific load needs to be applied and the current/voltage needs to then be within spec. Also, new batteries can be bad - it is rare but it can happen.

[KHE]

So I tested the draw last night. Not really anything there.

I got 0.005 A with everyting off. I then opened one door to see what happens, and the draw picked up a bit, but not much, up to 0.01 A

There is a terrible noise coming from the belt / and / or pulleys on the alternator side of the engine. Going to replace them all this weekend and see what happens.

Anyone know what the torque specs are for the idler pulley and the belt tensioner? I ordered the shop manual, but don’t have it yet.

Going to replace both plus the belt. If still a problem, guess will have to start measuring voltage drop.

Probably good idea to replace the pulley on the water pump side too, but that’s a job for another time.

Radio has a SOURCE button, so going to see if I can pick up a cheap CD changer this weekend!

Use a short length of 3/8" rubber hose and put one end close to your ear and move the opposite end all around the accessories & pulleys to isolate the source of the noise so you don't wind up replacing a bunch of parts that are still good.

[waterzap]

Will try the rubber hose trick tonight, thanks. Can always send the parts back before I install them.

For the battery, they had an Optima Red top in there. I have had problems with Optima before. In this case though my 78 Eldorado has a year old battery from Napa (Napa 84 or something). Will be using that one. Don’t drive the Eldo much. 12 mpg and a 27 gallon tank hurts a bit, so the Optima will go there for now.

Will post pics of the collection once I have enough posts.

[KHE]

Will try the rubber hose trick tonight, thanks. Can always send the parts back before I install them.

For the battery, they had an Optima Red top in there. I have had problems with Optima before. In this case though my 78 Eldorado has a year old battery from Napa (Napa 84 or something). Will be using that one. Don’t drive the Eldo much. 12 mpg and a 27 gallon tank hurts a bit, so the Optima will go there for now.

Will post pics of the collection once I have enough posts.

Great - I'd like to see pictures of your cars.

[waterzap]

How and where can I post some pics?

[waterzap]

So replaced the battery with a known good one. That helped a bit, but not much. Still had a lot of noise, and as far as I could tell it was the idler pulley. Replaced the idler pulley and drive belt. Much, much better now. Lights dont fade in the dark anymore. I think it was probably just the belt that was too stretched, and the idler pulley starting to go bad.

Voltage drop on negative was also very low. Did not test the positive yet.

Was thinking of replacing the accesorry tensioner pulley and / or water pump tensioner pulley and belt as well in time.

[KHE]

So replaced the battery with a known good one. That helped a bit, but not much. Still had a lot of noise, and as far as I could tell it was the idler pulley. Replaced the idler pulley and drive belt. Much, much better now. Lights dont fade in the dark anymore. I think it was probably just the belt that was too stretched, and the idler pulley starting to go bad.

Voltage drop on negative was also very low. Did not test the positive yet.

Was thinking of replacing the accesorry tensioner pulley and / or water pump tensioner pulley and belt as well in time.

Most of the time, the noise in the tensioners or idler pulleys is caused by the bearing grease that dries up. You can carefully pry out the seal and work some bearing grease in there while spinning the bearing. I use a small screwdriver with the sides of the blade ground to remove any sharp edges to pop the seal.

If the belts have not been changed and they have 100,000 or more miles on them, they're due.

You should be measuring the current drop on the negative lead - the ammeter must be in series (connected between the cable and the battery) to the battery terminal. You don't need to repeat the test for the positive side - the result will be exactly the same as the negative side.