Electrical Problems

[BodybyFisher]

I too have been following this.

I am very interested in the outcome.

It is like a good mystery story with the detective trying to catch the bad guy...but JUST BARELY MISSING HIM...every chapter.

Maybe a poor analogy...but it is all I can think of at the moment.

I can hardly wait for the ending.

Ditto Jim, GOOD analogy

[Cadillac Jim]

As far as I can tell, the only thing on the AMP fuse is the radio, and from there the power antenna. Bad radios are really rare, and since they are all computer-controlled, when they go bad they usually are just dead. The auto-retract of the antenna when the radio is off might conceivably be an issue. You can check this by unplugging the electric antenna motor and seeing of that does it.

[Phillip]

I am glad that somebody else is sharing my pain. I would especially like to thank Jim. Believe me, I know how much time it takes wading through the FSM. Mine is starting to get worn out. Hopefully in the end, this exercise will prove helpful to others.

Anyway, I was confused by the AMP fuse since I recalled that it was fed by the Retained Accessory Power system, but I found elsewhere that it is hot at all times on the Seville with the Bose system (which I have). However, I know that this fuse has an impact on the behavior of the PZM. I went looking for the electrical drawing of the Bose Radio and it provides conflicting information on the feed for the AMP fuse. I have been tempted to pick on the FSM in the past but I have found it was inevitably my mistake in the end, but this time I think they have a minor error. No problem now that I have found it.

With respect to the antenna, that has been a suspect for some time, since the retractor is broken so I left it in the up postion and unplugged it. What I am thinking now is that the computer is trying to lower the antenna but not getting a signal that it is down and this may be keeping the PZM awake. More reading is required on this one. I can't find all the inputs and outputs that affect the PZM, but they may be listed somewhere. Up until now I have been reviewing the DTC's to see if I can figure out what the inputs and outputs are. This is a slow way to go but it is leading to a gradually improved understanding.

Finally, I had mentioned earlier that one of the Maxi fused under the hood shut everything down. It is the Body 3 fuse which feeds the CLUSTER, RADIO/PHONE, PZM, AMP and COMFORT fuses as well as the Controlled Power and Controlled Power Backup Relays. No surprise here.

I hope to get some time to try a few more things this afternoon. I will keep you posted.

Thanks again,

Phillip

[Phillip]

Just a follow-up to my last post. I checked the drawing of the AMP fuse. It looks like it only supplies power to the four speakers. How can this keep the PZM awake. This is getting "curiouser and curiouser".

[Cadillac Jim]

The AMP ENABLE line to the radio is the ORN wire going to both Bose relays. Check these relays to see if they are warm when the car should be asleep. If so, pull these relays and see if that does it. If so, the RIM is not lifting the power to these relays when the radio should be OFF, or there is a short to power in that line. Or, the radio isn't truly going OFF.

[Phillip]

With each test taking over 20 minutes, I can't get much done, but tonight I did a few more checks. I confirmed that removing the AMP allows the PZM to go to sleep after 20 minutes. I confirmed this by waiting about 15 minutes when the load had dropped to 0.28 amps. This is the same load that is experienced indefinately if the AMP fuse is in place. I removed the Controlled Power Relay and the load dropped to 0.14 amps. With the PZM asleep, the load is 0.03 amps. The difference of 0.11 amps must be from the PZM, since I could not find any other fuse or relay that affected this (including the speaker relays).

From a review of the FSM, I cannot figure out how the AMP fuse affects the PZM. It only provides 12v to each of the speakers. I will do some more reading.

By the way, removing both the speaker relays had the same affect as removing the AMP fuse but removing just one (either one) had no affect. Also, I noticed tonight that the rear drivers side window doesn't work. I never noticed this before, but do not use the rear windows very much so I don't really know when this happened. It is probably irrelevant, but I thought I should mention it.

At least now, if I canl't find the problem, I can put a "kill switch" on the AMP fuse circuit and this will not be as annoying as putting on on the COMFORT fuse.

Thanks,

Phillip

[winterset]

another thought is to check various connectors / back of fuse boxes for corrosion. maybe remove a few key connectors, spray with wd-40, check each wire in the connector to make sure it's snug in the harness (by gently pulling it back to make sure it's locked in) - then re-connect & try another.

- since you mentioned the rear window, you might want to remove the switches from that door to verify there is no short there causing this.

currently I have a single pin in my amp that's causing my Left rear subwoffer not to work. I fixed it before, but obviously I didn't fix it good enough. I think removing this connector weekened the plug for that pin when I had it apart, I would have guaranteed it was OK but......

[Cadillac Jim]

In researching another post, I rediscovered section 8D in my 1997 FSM. ON 8D-3, the PZM functions and the inputs for the PZM wake-up are listed. The functions include RAP. The wake-up signals are:

• Key in Door Lock Switch
• Door Ajar Switches.
• Power Door Lock Switches.
• Trunk Ajar Switch.
• Trunk Tamper Switch.
• Ignition ON.
• Ignition ACC.
• Any Class 2 communications requireing PZM interaction (such as RFA).

That last is more than a wild card, it is a pack of Jokers. But if you are keeping your trunk lid open while you are checking, the PZM won't go to sleep. I don't know how to deal with this other than jimmying the switch closed or shorting it while you are testing.

The 0.11 Amps you are seeing is way more than the PZM would draw. It's likley another relay.

Section 8D also says that it does take about 15 minutes for the PZM to go to sleep, although many of the timeout clocks are 10 minutes. It also says that the Inadvertent Power is shut off when you open the door or whatever.

I think that the key is that you found that removing both, but not one, of the Bose relays solved the problem. Since we are talking about relay level power (about 0.1 to 0.2 Amps), I think that it may be the relays themselves, not anything on the relays, that is your last power drain. The complete schematic of the AMP fuse and these relays is on page 8A-150-9 in my FSM. These relays are turned on by the Amp Enable signal from the RIM, which is the ORN wire on terminal D2 of connector C2 on the RIM. That part of the schematic is on page 8A-150-8, the page facing 8A-150-9.

If the RIM is holding the ORN wire high to keep the Bose relays on, something must be keeping the RIM on. The RIM controls the speakers, the chime through the radio for the key in while the door is open and such, the CD changer, and the cellular phone. Basically, it controls the radio except for the antenna and tuner. Try pulling the RADIO/PHONE fuse and see if that doesn't do it. If it does, put it back in and see if the ORN wire to the Bose relays stays high after 15 minutes and the PZM is supposed to be asleep. If so, you may be looking at a bad RIM -- unless something else is keeping the PZM awake and it keeps the Bose relays on so the chime will go through the door speakers if necessary. In any case, it's the RIM module, not the PZM, that is staying awake and keeping your Bose relays on.

At this point, my money is on something like a bad door switch or trunk ajar switch keeping the PCM awake. Remember, something like a stuck key on your or your wife's fob door unlock button could be doing that.

If the PZM is going to sleep, it's the RIM that is staying awake. Check the codes and see if there are any network codes for the RIM. Even if there are not codes, check the connector pins for the purple wires on the RIM.

[Phillip]

Jim, you have been thorough as always. I have already checked all the inputs to the PZM with the acception of the Class 2 Serial Bus. All were OK. As for the Serial Bus, I am not giving myself much of a chance of figuring out what is going on in there.

I agree that the load is about right for a relay. There are so many relays in the car that I don't know where else to look. I removed EVERY relay in the trunk and engine compartment relay centers and this did not find it. I should point out that I removed EVERY relay at the same time. No relays left in either locations but still the drain continued.

I have successively removed the RIM, the RFA, the ACM, the SIR Module and the Amplifier. No luck there. You may recall that the interior is out of the car so I have access to lots of the electronic parts. Further more, all the connectors look fine.

I hate to admit defeat, but winter is coming and I still have a P0300 to diagnose and repair. With the information I have gleaned up to now however, I am starting to put together a plan.

I am thinking of putting a relay in the supply to the AMP fuse. I intend to activate this relay of the Accessory Time Delay Cut Off Relay (ATDR). That way, when the ignition is turned on, the relay will supply power to the AMP fuse. Then the ignition is turned off, the ATDR will keep the AMP fuse hot until the door is opened. Then the AMP fuse will go dead and the PZM will go to sleep as it should. On or the main challenges here will be to find a relay that can take the 30 amps that feed the AMP fuse. I should be able to find something that will do the trick.

I don't like to admit defeat, but at least this will retain the normal functionality. One aside. On another post, 1997Seville STS was trying to find a way to stop his door chime. I think that this will do that for me.

I would appreciate any critique of this plan. I can't think of any reason why it shouldn't work but if I am missing something, please stop me before I blow something up.

Thanks for your patience and I will let you know how it works.

Phillip

[Cadillac Jim]

I think that the relays are the Bose relays. We are not looking for something powered by them, we are looking for why they stay on.

The thing about the serial bus is that something somewhere else in the system could be telling the RIM to keep the speakers on. Whatever it is, it has to be either the radio itself or something related to a chime, which narrows it down to the key-in sensor, the door sensors, the seat belt sensors, etc.

[Phillip]

I agree, but I have removed the seat belt sensors, disconnected the resistor that was used to jumper the key-in sensor and checked the door sensors. All to no avail. Also, removing the Bose relays themselves, did not affect the load.

I feel like I have failed because I know there is a logical explanation for this but I can't find it. I can however, rework it so that I have the same functionality. I guess I will have to settle for that. Sorry.

[Cadillac Jim]

We may be running into the limitations of using posts to communicate and having different years in our FSMs. Didn't you say that removing the Bose relays cut the load to 0.02 Amps? I'm thinking Post #31 on Sept. 21 at 10:38 PM, paragraph 3. The other zinger is that keeping the trunk lid open will keep the PZM awake. Thus you probably have found the problem and solved it at this point without realizing it because you had the trunk lid open while waiting.

[Phillip]

Jim,

Let me clarify. With the Bose Relays removed, the load did not change right away. After 20 minutes, the load went away, from which I inferred that the PZM went to sleep when the Bose Relays were removed, but did not go to sleep when they were installed. Further, installing the Bose Relays once the PZM was asleep, had no affect (ie. the load stayed at 0.02 amps).

With respect to the trunk lid, I have always worked with the trunk lid down. Since the interior is out of the car, I have worked from the passenger compartment. On some occasions I would sit in the car, waiting 20 minutes to see if the PZM would go to sleep. On others, I would climb through the open window, Dukes of Hazard style.

My neighbours have always been suspicious of my sanity, but I really think they must be wondering now!

One other thought, I have been thinking about this relay idea and I am thinking of simply disconnecting the control circuit for the Bose Relays and conecting that to the Accessory Time Delay Cut Off Relay. That would be even simpler.

[Cadillac Jim]

My feeling is that modifying the electrical system on so complex a car can cause unpredictable problems. For example, the fuse for the Bose relays is a 30 Amp, so cranking it up with Moby's "Play" CD on deck can pop smaller fuses. If you have children, or even let a valet park your car, it can happen. No access to the CD player? No problem, they know where the "right" FM stations are.

If you are keeping the trunk lid closed, and the rest of the inputs known to wake up the PZM (door locks, door jamb switches, fob buttons, tampering and theft signals, etc.) are all OK, then, you seem to have exhausted the obvious. I did a final check on what's on the Bose relays using the schematics in section 8A-150 of the FSM and see only the powered speakers (the door speakers). The relays are themselves controlled by the PZM.

Just about the only things left that I can think of from here are the grounds and the connectors. You can check the wiring harness and the grounds, particularly the connectors around the doors and trunk lid, and find the grounds and make sure that they are all OK. But, I suspect that you did that long ago.

One last long shot is that a nearby RF source could be jogging the RFA. Things that can do that include, but are not limited to, the following:

• Garage door openers operated very near the RFA antennas in the rear and sides of the car.
• Radars, for the FAA or the military, within about a half mile of where you park the car.
• Another Cadillac key fob that is used very near your car at all hours of the night.
• A microwave oven within a few feet of the car, even through a wall.
• An FAA beacon, which is a sort of waypoint marker for aircraft.
• Nearby military installations with high-power specialty radars, such as an Air Force base, an active Pave Paws installation, etc. within about a mile.
• Nearby TV station transmitter antenna within a couple of miles.

Most of these things are out of the band used by the RFA but a strong enough signal can poke through the defenses of the RFA receiver and possibly jog it just enough to keep the PZM awake.

Before I disabled fuzes with switches, I would consider a trickle charger or battery tender. Here's a good one on Amazon that will sustain up to 0.75 Amp drain, more than enough for your insomniac PZM and it's parasitic friends:

Link to Amazon search page

The battery tender is the first thing on the page, for $24.99. Scroll down a couple of items and you will see a 25-foot quick-disconnect cable that will let you keep the battery tender locked indoors at night and make it very convenient to hook it up and disconnect it when you use the car, for $11.95. If you park in the garage near an outlet you won't need the extensin.

[Phillip]

Jim,

You raise some good points. Yes, I did check the grounds and electrical connections. I haven't diagnosed the power window failure yet and I will do to that before I tackle any modifications. You just never know what might come of that.

I have disconnected the RFA module and that had no affect.

I am expecially puzzled how the AMP fuse can have an impact on this. The absence of power to the door speakers seems like an unlikely suspect, unless there is a fault in the wires in one of the doors. I cannot find anything to indicate this, although I have not specifically checked the wiring with a meter. I think I will do that just to be sure.

With respect to your concern about fuses, I agree. I would never remove a fuse from a circuit. My intent was to simply put the relay in series with the fuse. This would involve a high capacity relay, such as a horn or headlight type relay. The second alternative that I am considering is to change the control circuit for the Bose Relays. This alternative would not have any impact on the high current circuit. In either case, the changes would be documented and reversible if they caused any problems.

I looked at the Battery Tender website. That is intriguing. We keep the car in the garage most of the time in the winter, so it would be reasonably practical. I will think about it, but I am becoming more fond of the relay idea. If nothing else, rewiring the relays gives me a chance to prove I am at least as smart as the car. Then again, maybe not.....

[Cadillac Jim]

I use a battery tender on my motorcycle, which sits much of the time. The owner's manual on the Cadillac says to put it in the storage mode if it's not going to be driven in more than a few weeks, and then to pull the battery. I think that a battery tender is a better solution.

[Phillip]

We don't store the Caddy. Even though it has been laid up all summer, we use the car as a daily driver most of the year. In the summer I have a 75 pontiac convertible and my wife has an old camaro, so I try to do all my heavy maintenance then, when we have the extra cars available. When they go into storage, we use the Caddy everyday. If you drove the car enough, the battery would not have a chance to rundown with the small drain, but my wife makes a lot of short trips around town and when the temperature dips to -20 or below, the battery doesn't really recover all that well without a good drive. The battery minder would solve this, but my wife is the primary user and might not be too happy with that. I suppose I could plug it in in the evening and unplug it in the morning. That's food for thought.

By the way, when I store the cars in the winter, I generally remove the batteries. I store the batteries in a cool place but the cars are stored in a cold barn. Well below freezing all winter.

[Cadillac Jim]

A charged battery has enough acid in the water to prevent freezing to some extent but I don't know how far down that protects them. The problems you hear about come from discharged batteries, which have less acid in the water and thus a higher freezing point. In any case I would still pull the batteries when storing the cars in an unheated barn for the winter. Then, keep the battery tender on them so that they will be in tip-top shape in the spring, and you will get the 5++ years of life out of them that you would expect in mild climates.

[Phillip]

Yes, I have never seen a battery freeze, but I guess I would like to keep it that way. I don't trickle charge my batteries in storage, I simply set them aside and wait for spring. I don't usually even charge them before reinstalling. I have never had a problem. Would the batteries last better if they were trickle charged?

[Cadillac Jim]

Yes, letting the batteries self-discharge over the winter shortens their life. You need a real battery tender, though, not a trickle charger. The difference is that a battery tender is more complex (usually with a microprocessor and often with temperature sensors for the battery, a precision ADC for measuring voltage and another for measuring charge current, a programmed strategy to avoid overcharging and water boil-off, etc.) while a trickle charger really needs to be taken off most of the time and put back for 24 hours once a month or something to avoid boiling off the water.

[Phillip]

Hmmm. That is interesting. As you may have been able to figure out, I am not an electrical guy. I am learing alot now though. I may have to go shopping for one of these. I assume you can get ones that condition multiple batteries.

[winterset]

Does your car have "storage" mode. It'll be a good test to see if by putting the PZM in a suspended state you still have the issue. other thing to check are the thick power cables. I think we had a member here have a oxidizing power cable that was drawing current.

[Cadillac Jim]

All Cadillacs since at least 1995 have a storage mode. I believe that you enter the storage mode by using an override code. Most people just remove the battery, and the FSM recommends that if your car is not going to be driven for more than a few months. The storage mode bridges the gap between "two weeks" and "a few months." But a battery tender bridges the gap between "two weeks" and "several years" seamlessly.

There are a lot of battery tenders out there that handle multiple batteries. Stores and service facilities that sell a lot of batteries commonly use them and have for a whole lot of years. Battery tenders for individual batteries and quick-disconnect tenders for individual vehicles are a recent thing, affordable ones appearing for motorcycles just a few years ago. The circuitry is pretty common and it is used for electric wheelchairs and such internally. Whenever you see "leave plugged in all the time when you are not using..." there is a battery tender in there somewhere. Chip manufacturers make a variety of battery-tender-on-a-chip products and that implies that there are a lot of them used in manufacturing things.

If you have a wife or others who occasionally drive the car, or you yourself have been known to forget little things occasionally, I would use a quick-disconnect cable and rig it up through the gap over the top of the radiator so that it unplugs harmlessly if someone just backs the car out to use it and forgets the battery tender.

Check your local auto parts and tools outlet for battery tenders for multiple batteries. If you want a small one for just one vehicle, inexpensive ones are still hard to find, which is why I found one and posted a link; your best bet in brick-and-mortar is a motorcycle shop but I would shop online where there is more variety and competition.