Cadillac Owners Forum banner

'99 Concours Battery Drain - Amp circuit culprit - questions regarding circuit

6K views 9 replies 3 participants last post by  rodnok01 
#1 ·
My '99 DeVille Concours is totally stock and includes non-Bose in-dash CD stereo system. Car was going dead in storage mode (when stored a week or so) and now goes dead overnight when car isn't stored. Two new AC Delco batteries in less than 4 weeks and then finally determined a serious parasitic draw. Unplugged the 30 amp fuse from trunk-mounted fuse block which was marked "AMP". After four days the car has retained power and has not drained down overnight or over this period. Car has not been driven during this test. Started twice and let run less than thirty seconds both times within this period so alternator hasn't "recharged" the battery. Voltage shown on dash display states 12.6 volts prior to starting and remains as such when turning ignition on (without starting the engine) during this period with the fuse pulled. So...long story short my unplugging the fuse has eliminated the drain. It is on this circuit.

Question #1: How or why would the amp circuit be "hot" and not switched power? Is this due to security system, phone or chimes...etc.?

Question #2: Is the amp powering up when it shouldn't (car off and parked) or is this the factory phone? I have seen a post or two that these amps (behind back seat) go bad but don't understand how it can go bad and power up...is there a relay or control module that may be causing this? Also seen a post regarding the phone. But no definitive answer so this is prompting my questions to the forum.

Question #3: While in the trunk and with rear electronics tray pulled down [made of plastic and where amp, PZM (I assume this is the unit on the driver's side above the relay bank; perhaps I am incorrect in calling it a PZM?) and other units including fuse block mounts and resides within], I was hearing and also felt a clicking from what I believe is the PZM every minute and a half or so...is this the control of the Amp?

Question #4: If there is an Amp issue causing it to power up when ignition is "off", is there a way I can convert this to a switched condition? Stereo sounds and operates fine when Amp fuse is installed so I believe the Amp itself could still be used if it could be switched if indeed the Amp is the culprit.

Thank you in advance for any advice and help.
 
See less See more
#2 ·
If you have in-dash CD you have BOSE.
1. The RIM (Radio Integrated Module) witch is what you call AMP is powered from the RAP circuit for 10 minutes after the ignition is turned OFF or until any door is opened.
2. There are 2 BOSE relays behind the rear seat (also where the RIM is located) witch are controlled by the RIM directing the power from the AMP 30 A fuse to the final stage amplifiers.
3. Not sure where exactly the RIM is positioned on the rear electronics bay (that plastic shelf) but my guess is dead center and UP. Should be the largest module in there also the case is sheet metal. The PZM is what controls the RAP relays providing power to the RIM and is located on the passenger side of the rear electronics bay (a black plastic case module).
4. You can put a switch on the control wire for the BOSE relays if you want to ruin your car. The real fix is PULL the codes, see if you have U codes. Test the RAP circuit, test the BOSE relays, check the ignition cylinder. You need serious electrical knowledge and a FSM.
Suspected modules: Ignition cylinder, PZM, RIM, HU, wiring between and the 2 BOSE and 2 RAP relays.
 
#3 ·
I pulled the codes; had an interesting experience while doing so.
To update the case, I have pulled the 30A fuse for the "Amp" and drive car locally without radio. Has not drained the battery since the last time I posted in 2011. When taking car on a trip I plug in fuse and remove it once at destination. No problems occur while driving. Battery doesn't drain.

So yesterday, I started pulling codes. Prior to I plugged in the 30A fuse into the "Amp" fuse location. Car started fine, all systems "go".
I then shut off the car. Turned the ignition back on and began accessing codes. The following codes (historical) were listed:
No PCM codes; No IPC, No ACM, No SDM, TCS, RSS or PZM codes were cataloged/recorded.
IRC produced U1300, B1983, U1129 and U1064 were recorded "History".
No RFA nor CCP codes were recorded.
MSM produced B2112, B2111, B2119, B2120, B0856 and B1983 "History".
No MMM codes.
IPC produced B1552 "History" and B1983 "Current".
ACM produced B1983 "Current".
No PHN codes.
SD produced 1327 "Current"; I believe this was also a "B" code.
No PCM codes.

Now what is interesting; as I hadn't pulled codes before I was trying to write down circuits, codes, etc. while this was all flashing across the dash. I missed a couple of prefix codes (like the letter "B") so I ran through the codes again. Keep in mind that the 30A fuse was installed during this process. (About an hour earlier, as a test I started the car with the fuse in, got out of car, had the radio playing, shut the door and thru the window turned off the ignition and pulled the keys out of the ignition. Approximately 10 minutes later the radio stopped playing. I believe the RAP circuit may be OK due to this test but that remains unknown.) While running thru the codes again, the battery started dying and the lights and dash started dimming. I started seeing differing codes as "Current". As running thru the codes this second time the battery died and everything went dead. I charged the battery and ran thru the codes a third time; here are the different codes recorded:

IPC B1552 shown as History but wasn't listed on 1st run thru; B1983.
SDM B1327 shown as History but wasn't listed previously.
PZM B1550 or 1552 (can't read my writing though it's most likely B1552); B1983.
IRC U1129 Current (was shown as history previously).
RFA U1300 shown as History but wasn't listed previously.

MMM now shows B1983.
PZM now shows B1552, B2120 and B1983 as Current.
RFA now shows U1300 as History (not shown previously). Perhaps these "new" codes shown as "history" on this third attempt is due to them being recorded while the car was dying on the second attmept and when re-charged running thru the codes again (the third time) it went from current to history.

I'd appreciate any help. Some of these codes (B2111 thru 2120) refer to the lumbar support sensors which I believe the timer portion of the switch may be bad...but that has been bad for a while. I am not sure that is related to the 30A "Amp" circuit of which I have had to pull the breaker to mitigate the discharging of the battery. I would like to find the fix on this lumbar at some point. If any ideas as to what component I need I'd appreciate the advice.

The B1983 code = "device power circuit low" (what device?) The same for B1327.
B1552 = Keep alive memory (KAM) error.
U1300 = class II short to ground...what is class II?
U1129 = loss of communication with Amp; I believe this to be caused by my pulling of the fuse.
U1064 = loss of communication with DIM; what is DIM? (not RIM)
B0856 = battery 2 out of range...?
 
#4 ·
Class II refers to communications lines, shorted to ground not a good thing and could be responsible for a lot of the codes I bet.
Low voltage causes system to throw all kinds of codes.
I would clear all the codes (with amp plugged in) and see what comes back.
Amp very well could be fried and not shutting off.
 
#5 ·
OK. I've cleared all codes.
I left the 30A fuse in the "Amp" position (fuse block in trunk) when clearing codes and also left the fuse in for a couple of hours when I ran some errands.
Came back to the car and pulled codes; no codes found on all circuits: PCM, IPC, ACM and the like. Ran thru all circuits and no codes were recorded.
Then I went to start the car...starter solenoid clicks, trunk popped open and horn sounded, lights flashing...the same crap...no start and seriously drained. Ran thru the codes prior to it
totally dying and these were recorded:

IPC B1552 and B1983 (both as History rather than Current which I thought was interesting...)
PZM B1552 also recorded as History.

No other codes found.

According to OBD the code B1552 is KAM Error (Keep Alive Memory) and B1983 is Device Power Circuit Low.

So does this tell me anything?
 
#6 ·
Unfortunately doesn't help a lick. I think the Low voltage and KAM codes only go History IIRC.
You could unhook the 2 non power connectors at the amp and see if it still draws it down. If it does amp prob shot, if not possible HU is not telling it to shut off?
Does your car have the cell phone option? Trying to remember if/where I saw an issue about them causing problems. But to be honest might be crazy or mis remembering. That was comfort fuse issue I believe though.

Sounds like the AMP is bad(not uncommon) and not shutting off like it should.
 
#7 · (Edited)
Ok...another update.

Same codes are recorded when battery drained: IPC B1552 and B1983; PZM B1552 and IRC U1129 (loss of communication with AMP).

In my attempts to determine if the AMP is the culprit component, I disconnected the 24-pin connector from the amp last night. With the 30A fuse installed (amp circuit) the battery did not drain. The 32-pin connector was still intact; plugged into the amp.

If I am correct, the 24-pin is an "out"...
Further, I believe the 32-pin is an in/out. So I am assuming that something on this connector (32-pin) is causing the battery drain.

Now what? How can I isolate and determine which component is causing my battery drain?
 
#8 ·
Below is copied from FSM for 24 pin connector.
Since it has Serial data lines in it the HU may even be the culprit since it may not be telling AMP to shut off.
The only other wires I'm not sure where they go or what they do at this point are the remote Audio Signal wires.

There was 1 instance I found google searching that HU was bad. Perhaps another member can chime in(N*Caddy may be the only one who can answer and you may want to PM him)

**************************************************************

A1
--
--
Not Used

A2
ORN
1853
Speaker Feed, Right Front (Midrange)

A3
RED
1955
Speaker Return, Right Front (Midrange)

A4
--
--
Not Used

A5
TAN
1855
Speaker Feed, Right Rear (Midrange)

A6
LT BLU
1957
Speaker Return, Left Front (Midrange)

A7
--
--
Not Used

A8
DK BLU
1857
Speaker Feed, Left Front (Midrange)

A9
WHT
1959
Speaker Return, Left Rear (Midrange)

A10
--
--
Not Used

A11
WHT
1859
Speaker Feed, Left Rear (Midrange)

A12
--
--
Not Used

B1
DK GRN
1953
Speaker Return, Right Front (Midrange)

B2
PPL
1807
Class 2 Serial Data Line

B3
PPL
1807
Class 2 Serial Data Line

B4
DK GRN
1947
Audio Return, Left Front, Low Level

B5
TAN
511
Audio Signal, Left Front, Low Level

B6
LT GRN/BLK
1948
Audio Return, Right Front, Low Level

B7
LT GRN
512
Audio Signal, Right Front, Low Level

B8
BRN/WHT
367
Remote Audio Signal, Left

B9
BLK/WHT
372
Remote Audio Return

B10
--
--
Not Used
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top