Some posts ago the words "Sony CD Changer" were mentioned.

The Sony CD changer in my SE stays powered up and drains the battery unless I remove the faceplate from the Sony head unit.

At least one battery and lots of head bashed against brick walls went into discovering the cause of the "random" leaking battery.

One other thing I have noticed is that for reasons I can't fathom on both my '88SE and '90GT if the doors are left unlocked the battery drains faster. I have electrical work to do on both vehicles!

Jon

 

Okay, a small spanking first. I advised back on page three to check for the correct relays, not just a relay.

Now on to the work at hand. It sounds like you've got a primary wire issue. Before going off digging in to wiring, clean the jumper post with a small wire brush. Also clean your ground connection on the block or chassis. Recheck the voltage at the jumper. Wait for a while, and make sure that voltage is stable.

Now while it's connected, try to start the car. Watch the voltage, it should decrease to around 10 volts, but bounce back after the car starts. Allow the car to idle, look at your generator light, note if it is on. Watch the voltage as the car idles, it should rise from 10 volts to about 13.5 volts in less than a minute. If it does not, you have a problem in the charging circuit, which would help to explain all the other goofy things you've got going on(except the bulb). Another possibility is a near short from one of the heavy wires to the relay panel, or to the jump block. That will turn on the gen light as well.

If the voltage at the jumper point rises to around 13.5 volts, and the generator light is on, rev the car a bit and watch the light. If it goes off, you have a generator or regulator issue. I didn't know these cars had a generator, and not an alternator until checking the WSM. You may want to buy a set of brushes for the generator anyway, as it's a good idea to replace them. easy job. If you can find a regulator nearby, replace that as well, there is no troubleshooting to be done about a regulator. It's just a few relays in a box that regulates the curent flow to the batt.

Now, the starting problem. Start with a fully charged battery, Check relay XV. If you have a relay with the same PN, swap them. Hook the meterr to the jump post, record the voltage. Must be at least 12 volts. If less than that, you have a defective battery. If over 12 volts, turn on the key, but don't start the engine. Keep your feet off the brake, doors closed, and watch the voltage. It will slowly decrease as the load on the batt takes power. This is a bit tricky, but it shouldn't decrease too much too fast. Hard to quantify, but if it goes to around 10 volts in a less than a minute, you've got a problem in the battery, or in the starting circuit.

It's possible you have an open in the large wire from the starter to the jumper. another thought is the ignition switch. I have seen them fail intermittantly before.

I haven't discussed the ground circuit yet, but it's another possible issue. If you can, get the car started and take if for a drive of more than 20 miles in the daytime. When you get back, leave the engine on, and recheck the voltage at the jumper. If the gen light comes back on while it's idling, you definantly have a generator or regulator issue. If not, and the voltage will stay near 13.5 volts, the charging system is fine, but you could still use brushes in the generator.

So, relay XV, gen brushes, regulator, ignition switch, bulb or wiring to bulb, possible open or even a short in the big line to the jumper block(hard to trace).

Try to work one cicuit problem at a time. We've got your resting current draw under control, and we'll get the rest of them.

Doc

 

Great advice. This may turn in to a big job, so I'll probably tackle pieces at a time.

One of the things that's most frustrating about this is that I have events tentatively scheduled each weekend this month for this car. A charging problem is scary about that; I don't want to be stranded somewhere. Saturday I'm supposed to be tagging along with a Lotus Elise club on a 60 mile run. The next week I'm going to my high school reunion 250 miles away, but the advantage is that my brother is in the area and has a full shop with a pit and was a Porsche owner. The next weekend is Sharktoberfest (5 hours round trip), and the week after that is a run to Malibu (2 hours round trip) with the local PCA chapter.

Am I crazy to try any of that stuff like this? You mention a 20 mile trip as part of a test; the Saturday run could qualify, and I'd have others along. Although you know I'd catch it from the Elise guys if my 928 dies. But it *does* seem to be generating enough power to run the car; retaining it is another story.

 

Doc has some great advice there. I know I'm going to end up repeating some of his advice and speculation, but I'll do my best to address your questions from my perspective.
Low idle, meaning what RPM? Is this Auto or Manual? I had to increase my idle to the top of the spec(850RPM) to get it to charge sufficiently at idle.

First of all, charge the battery fully. Check the voltage, then check the voltage at the battery posts while cranking. It should not drop under 10 while cranking. Note that voltage, and check the voltage at the jump terminal while cranking. It should be pretty close to the voltage you measured at the battery. If not, then there is a problem with the primary + wire or one of its connections. This test is likely to give you very different results depending on whether you are cranking it or not -- you may have to put significant load on the circuit to see the voltage drop.

If you find a large difference in voltage on these two tests, I'd suggest putting the car up on ramps and checking the condition of the main positive cable from end to end. Look for signs that it's heating up or that either end connection is coming apart. Check the ring terminals on the starter, alternator, and jump post(with battery disconnected). Clean and inspect all of them. If the wire is marginal, it can heat up, drawing more and more power. The starter could be at fault too, heating up with use which makes it draw more power, draining the battery quickly. It could be a combination of these things to one degree or another, with low charge at idle and bad wires preventing the battery from charging as well.

My car idles with a wonderful, even growl at 750rpm. I haven't tried balancing a nickel on the plenum while it's running, but it's smooth as butta. Won't charge enough at idle though. At 850, it charges enough, but has a bit of a lope to it. As much as I prefer the sound of the lower idle I don't think it's practical. Your mech. may have set the idle to where it runs smooth so you would like the way it runs. Try increasing it to the top of the spec, 850, and see if that helps.

Only the drain, dead battery, and reduced capacity of the battery due to sitting discharged. Your new battery can have it's capacity and life shortened considerably if you leave it discharged. Put it on the charger ASAP!

Side issue... don't let it distract you. We can address that later. Or do a search.

I wouldn't recommend that... put it on the trickle at night when you are done messing with it. Sometimes a dead battery will recover somewhat if left sit for a while, but it does damage to the battery. Keep that new battery new, keep it charged!

Maybe, but that's a side issue... unless you got a tiny honda-sized battery from the worst possible manufacturer, just about any car battery will work well enough for you to troubleshoot it. If it's the wrong one, swap it for the right one.

 

I'd call off the 60 mile run and spend the time tracking this down. But that's just me.

 

Where exactly is the jump post up front?
I have worked a bit on my draining battery issue, checked Batt=12.62V, with car running it's 13.93V, so it is charging. My neighbor will be by this weekend to find the amount of the current drain, I am begining to suspect the stereo. If I have to live without a stereo that is fine, too many friggin speakers to replace anyway.

 

Jump post is a hex shaped piece on the passenger side inner fender. You will see a large electrical cable connected to it as well as some smaller ones. There should be a small plastic cap on it may not be there. ( I would suggest getting one if it is not, drop a wrench on it and you will get a big surprise)

 

Thanks that is what I thought that thing was for.

 

The cranking power did not recover last night, so it is back on the charger.

I love all this step-by-step diagnosis stuff. Thanks. Unfortunately getting the car up on ramps is beyond what the condo association will allow. I'm afraid anything like that will have to be done by the mechanic. I believe that means the brush replacement and pos cable replacement. But at least I can do all the testing and try and answer some questions.

It's also very much a relief to know that the low idle (yes, RPMs) with no charging might be a somewhat common thing. I would suspect the idle is currently in the 5-700 range. I love the low idle, but if it's impractical it's impractical.

 

I was having the "battery drain problem"too....My car would not jump start, and have a very hard time load testing over the jump post! After swapping batteries, I found that my negative battery cable was not getting a good ground. I replaces with a new cable, and WOW problem fixed!!!

 

FWIW, I have no trouble getting a jump start from the jumper in the engine compartment.

 

Dave added some good stuff. Step by step is good. I don't think the 60 mile run on Sat is a good plan, unless you have a 5 speed, and don't mind a push start if it won't crank. Beware, you may not have enough battery reserve to make 120 miles R/T.

Kurt mentioned the primary cable to the chassis from the negative post, that could do it, so check that one, and clean under the strap, then reattach.

Battery check: 12-ish volts with key off, doors closed at the CLEAN jump point.

Batt load check: Leave meter on jump block, turn on key, watch voltage decrease SLOWLY.

Gen/reg check: Leave meter on, start engine, let idle, watch voltage on meter rise to at least 13.5 V. Check GEN light in car. If on, rev till it goes off.

Gen load check: Rev engine and maintain 2200RPM. Watch meter approx 13.8 Volts. Turn on lights, check meter, turn on heater blower, check voltage, turn on wipers, check voltage. The voltage should not fall below about 13.5 with all listed acc on. Let idle, watch meter, it will fall to about 12-13-ish volts, it should not fall below 11 with the acc on at 850RPM.

Doc

 

They may have a rule about mechanical work, but not about cleaning & inspecting. Tell them you are cleaning & inspecting.

 

Actually, they have a rule about cleaning too. Ever since the drought about 10 years ago, using community water to clean cars has been against the rules. They never relaxed the rule after the drought was over. They're really a bunch of *****.

Basically, anything that puts stuff on the ground to be cleaned up is an issue. Putting a car up on ramps would just be asking for trouble. All the parts I'm taking off the do work - carpets, padding, etc., goes into the back seat while I'm doing the work.

 

Sounds like it's time to move.