1999 Chevy (S-10) Blazer. One day, shortly after running the vehicle the instrument panel lit up like a Christmas tree. Everything flashed on and then return to normal. It was no big deal until the car wouldn’t start one afternoon. But when I tried it again in a half hour, it started up, no problem, although I was treated to another light show.
I thought it was a battery problem, so I replaced the battery. Everything went back to normal except the radio would not work. I couldn’t set the clock, and the radio LED read “loc”.
I decided that the lack of a radio was not going to stop me from my assgined routes and went on with life.
At least for a little while. A week later the instrument panel lit up and flashed on and off then the car died completely.
Now when I turn the ignition to “on”, the insturment panel lights up, all the gauges read normal, except the voltage meter reads 8.5V. When I turn the ignition to start, everything goes dead. Nothing, nada, kaput. I can repeate this process hourly, but then my wife pointed out that performing the same tasks under the same conditions while expecting a different outcome is the basic definition for insanity.
So I have turn to you, the e-world of magical mechanics and car crazies; what is my problem?
"Insanity!"
Your wife is correct, as usual, sorry.
Well either the battery has a very low charge on it or there is a wire connection problem between it and the main power panel under the hood. I suggest you first clean all the battery connections using a battery post cleaning brush. If that doesn’t help then you be able locate the faulty connection by tapping on suspected trouble areas with a screwdriver handle.
I worked for GM in 99 and I was dispatched a 99 S-Blazer with the complaint very similar to yours but not exact.
The complaint was that all the warning lights,tach,spedo etc. would “freak out” that is go wild,flash,needles sweep and stop and return to normal.
I could not duplicate,sent the car away,the customer returns,he was on vacation and his wife was taping with a video camera, the scenery,the cluster acted up, they got it on tape.
I replaced the entire under hood to cluster harness.
Car never returned,I don’t know if my fix was the reason the car never returned
The radio has the Theft-Deterrnt feature enabled. Here are the instruction’s from my 2000 Blazer User’s Manual
Theft-Deterrent Feature (If Equipped)
THEFTLOCK is designed to discourage theft of your
radio. It works by using a secret code to disable all radio
functions whenever battery power is removed.
The THEFTLOCK feature for the radio may be used or
ignored. If ignored, the system plays normally and the
radio is not protected by the feature. If THEFTLOCK is
activated, your radio will not operate if stolen.
When THEFTLOCK is activated, the radio will display
LOC to indicate a locked condition anytime battery
power has been interrupted. If your battery loses power
for any reason, you must unlock the radio with the secret
code before it will operate.
Activating the Theft-Deterrent Feature
The instructions which follow explain how to enter
your secret code to activate the THEFTLOCK system.
It is recommended that you read through all nine steps
before starting the procedure.
If you allow more than 15 seconds to elapse between
any steps, the radio automatically reverts to time and
you must start the procedure over at Step 4.
-
Write down any three or four-digit number from
000 to 1999 and keep it in a safe place separate
from the vehicle. -
Turn the ignition to ACCESSORY or RUN.
-
Turn the radio off.
-
Press the 1 and 4 buttons together. Hold them down
until — shows on the display. Next you will use the
secret code number which you have written down. -
Press MN and 000 will appear on the display.
-
Press MN again to make the last two digits agree
with your code. -
Press HR to make the first one or two digits agree
with your code. -
Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display will show REP to let you know that you
need to repeat Steps 5 through 7 to confirm your
secret code. -
Press AM-FM and this time the display will show
SEC to let you know that your radio is secure.
The LED indicator by the volume control will begin
flashing when the ignition is turned off.
Unlocking the Theft-Deterrent Feature After a
Power Loss
Enter your secret code as follows; pause no more than
15 seconds between steps:
-
Turn the ignition on. LOC will appear on the display.
-
Press MN and 000 will appear on the display.
-
Press MN again to make the last two digits agree
with your code. -
Press HR to make the first one or two digits agree
with your code. -
Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display will show SEC, indicating the radio is
now operable and secure.
If you enter the wrong code eight times, INOP will
appear on the display. You will have to wait an hour with
the ignition on before you can try again. When you try
again, you will only have three chances to enter the
correct code before INOP appears.
If you lose or forget your code, contact your dealer.
Disabling the Theft-Deterrent Feature
Enter your secret code as follows; pause no more than
15 seconds between steps:
-
Turn the ignition to ACCESSORY or RUN.
-
Turn the radio off.
-
Press the 1 and 4 buttons together. Hold them down
until SEC shows on the display. -
Press MN and 000 will appear on the display.
-
Press MN again to make the last two digits agree
with your code. -
Press HR to make the first one or two digits agree
with your code. -
Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display will show —, indicating that the radio
is no longer secured.
If the code entered is incorrect, SEC will appear on the
display. The radio will remain secured until the correct
code is entered.
When battery power is removed and later applied to a
secured radio, the radio won?t turn on and LOC will
appear on the display.
Don’t put too much faith in the dash guage. Check the battery voltage across the terminal with a multimeter. A fully charged battery should read about 12.6 Volts. With the engine running the voltage should be 13.5 to 14.5 V.
If the battery is partially discharged you may experience driveability problems. My Blazer’s idle was ~150 rpm higher than normal and the torque converter lockup would not engage when the the battery was at 25% charge (12.1 V).
Ed B.
Most probable: I think you have an intermittent short somewhere in your electrical system or accesories. That would cause the low voltage reading. A quick spike in voltage also resets computers and the radio’s Theft-Deturrent.
Less probable but possible:
A shorted cell or two in the battery - also causes low voltage.
A flaky or loose battery connector or battery wire to ground.
A helpful test - When the battery reads 8.5 volts, disconnect a battery cable and measure the battery voltage directly. If it’s still close to 8.5 it’s the battery. If the direct voltage is 12 or above, it’s a short somewhere.
I like mbogart’s troubleshooting step.
However, I’m going to side with a low battery, possibly due to a bad alternator, or a high resistance connection. Possibly a corroded cable. My reasoning is that a short to ground would typically create a parallel circuit path, and while that might cause havoc the existing meter path would still read 12VDC. A high resistance connection would be in series and drop voltage.
Tough call, however. Weird things can happen with shorts. They can completely alter circuits, putting a resistive circuit in series with the meter circuit. It’ll be interesting to see the final solution.