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28 Posts
Discussion Starter · #1 ·
Strangely, my stereo stopped working the other day. I have a well maintained 98 Deville with the non-Bose cassette deck with CD changer.

When I got in the car and turned on the ignition the strereo's display was blank at first, the the "2H" came on to indicate it was retreiving it's memory presets, then it went blank again. The power/volume knob was in the "on" position. I pushed the knob in to " "off" then push it "on" again. This time the clock display appear showing the correct time, but none of the other functions work. I tried pushing every button to no avail. I even tried putting a cassette tape in, but the stereo work not accept it as if it was not turned on (however the power switch was still in the "on" position).

Everytime I start the car the same thing happens; display blank until I turn it "off" then "on" again, then only the clock with the current time displayed.

What is going on??? Is my stereo dead?


28 Posts
Discussion Starter · #3 ·
Thanks for the ideas.

I don't think "2H" is an error code. The "2H" was nothing new. The manual says the "2" is for memory setting "2" and "H" is for the "home" presets. I'm pretty convinced that is OK.

Checking the fuse is a good idea. Where is it? I looked in the fuse panel and didn't see one marked anything like "radio". Also, the clock still works and keeps time and the switch powers it off and on. It seems like it's getting power, but there may be another fuse somewhere besides the one for the main power.

28 Posts
Discussion Starter · #6 ·
Problem solved!!!

Well, I got back into the car to check for codes after pulling the fuse and the stereo was working, again. I guess pulling the fuse reset it somehow.

I'm stil puzzled as to what happened in the first place...

Cadillac Technician
11,038 Posts
Well if you have UQ6, and maybe if you don't.... here is what is happening. I see this problem a lot on newer cars.

The Radio and Amplifier are "class 2" devices. What this means is that they communicate on the Class 2 communication bus, the vehicles main line basically. Radios and climate control used to use a separate "E&C" or entertainment and communication bus. But I digress.

GM figured out a few years ago, rather than run a bunch of wires to all the modules on the cars, they could put one in charge of telling all the others when the key is on. This is called the "Power mode master". When the key is turned on it sends out a message on the bus telling all the modules to "wake up". That way all they have to do is supply 1 "hot at all times" power and sufficient ground to each module and it eliminates the separate ignition feed.
With that in mind, what happens is when you turn the key on the radio is waking up, but the amplifier is not. When you try to turn on the radio it sends a message to the amplifier but the amp is not awake, the radio sees this condition and thinks it must be mistaken for being on and it shuts itself back off and displays the time only. It will also set a U1000 communication code because it can't communicate with the Amp.
This condition is known as "logic lock". Meaning, the software in the amp has confused itself and it's ignoring the messages from the power mode master and not turning on. Pulling the fuse resets the "logic" in the amp and now it works.
If the car was under warranty I'd replace the amplifier for you. If it's coming out of your pocket, I'd wait until it does it 2 or 3 times before dropping the cash. Those amps can be expensive depending on your options package.
They are not hard to do for a pro, but for a novice it would take some doing.
It's mounted behind the rear seat back, which is easy to get out.... if you know how ;)

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1998 Deville D'Elegance
133 Posts
ewill3rd, can you explain how to figure out how many speakers the car came with factory? I belive I have the 11 speaker system but I don't see any amps (haven't removed anything just looked in the trunk)... I'm brand new to Cadillacs and loving this forum and hope you can shed some light on this... I'm guess when you say UQ6 you are referring to a production option. On GMC medium duty trucks the put this list on the drivers side sun visor. Obviously they aren't going to do this on a Caddy so where is the list and where can I find a breakdown of the option codes?

Cadillac Technician
11,038 Posts
The SPID label (RPO code label) on a 98 Deville should be in the trunk, likely under the spare tire cover, usually located towards the bottom.

Entertainment system RPOs usually begin with the letter U.
Here is a list of RPOs for '98 Deville entertainment systems.

I think I see UQ6 as the 11 speaker system.

If you can't find the label, give me the last 8 digits of the VIN and I can look it up for you.

Theft Deterrent Sys

Alarm Vehicle Speed, Universal

Opener Garage Door, Universal

Radio AM Stereo/FM Stereo, WX, Seek/Scan, Auto Rev Music Search Cass, RDS, CD, Clock, ETR

Radio AM Stereo/FM Stereo, DSP, Clock, ETR

Radio AM Stereo/FM Stereo, Seek/Scan, Auto Rev Music Search Cass, MCD, Clock, ETR

Radio AM Stereo/FM Stereo, DSP, WX, RDS, Seek/Scan, Auto Rev Music Search Cass, CD, Clock, ETR

Radio AM Stereo/FM Stereo, DSP, WX, HPS, RDS, Seek/Scan, Auto Rev Music Search Cass, MCD, Clock, ETR

Speaker System Bose, 4

Speaker System 11, Quad FRT DR MTD, Quad RR DR MTD, Dual RR Package Shelf, Center I/P, Amplifier

Radio AM Stereo/FM Stereo, Seek/Scan, Auto Rev Music Search Cass, HPS, Clock, ETR

Antenna Windshield, RR Window, Radio

Speaker System 6, Dual F/D Tweet & Woof, Dual Ext Range Shelf

Speaker System 8, Dual F/D MTD, Dual RR DRS, Dual Mirror Patch CTR I/P, Pkg Shelf, Amplifier

Speaker System 8, Bose, Dual F/D MTD, Dual RR DR, Triple I/P Pkg Shelf, Amplifier

Navigation System Display

Cluster Kilo & Miles, Mechanical Display

Cluster Inst, Kilo & Miles, Digital Speedometer Display

Horn Noise Regulation

Horn Four Note

Radio AM Stereo/FM Stereo, Seek/Scan, Auto Rev Music Search Cass, Clock, ETR

Radio AM Stereo/FM Stereo, Seek/Scan, Auto Rev Music Search Cass, CD, Clock, ETR

Player Multiple Compact Disc

Speedometer Inst, Kilo

Speedometer Inst, Kilo & Miles, Kilo Odometer

Antenna Power, Radio
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