Blinking Parking Brake Light - S-10 Forum
 
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post #1 of 26 Old 01-24-2010, 09:47 PM Thread Starter
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Blinking Parking Brake Light

I have a 1989 S10 4wd 2.8 5sp and the parking brake light in the dash is blinking. The light will do four short blinks then a long blink, then repeat. it does it whenever the truck is running. The parking brake hasn't worked on it since I got the truck six months ago. Would it be throwing a code that I need to check? I have no idea why it is on, just want to figure out if it is something I need to fix.


Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #2 of 26 Old 01-25-2010, 04:06 AM
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Re: Blinking Parking Brake Light

that is the way the RWAL tells you the code...when mine started flashing I just unplugged the module under the dash that is on the inside of the fender.
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post #3 of 26 Old 01-25-2010, 08:59 PM Thread Starter
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Re: Blinking Parking Brake Light

What is the RWAL?

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #4 of 26 Old 01-25-2010, 09:44 PM
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Re: Blinking Parking Brake Light

Rear Wheel Anti Lock
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post #5 of 26 Old 01-25-2010, 10:39 PM
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Re: Blinking Parking Brake Light

Jump A and H on the ALDL and watch the light for the code, report back.


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1989 Chevrolet Blazer 4.3 4x4
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post #6 of 26 Old 01-29-2010, 04:50 PM Thread Starter
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Re: Blinking Parking Brake Light

Which is port H? I've jumped A and B and I have no check engine light codes. What do I need to look at to check my blinking parking brake light?

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #7 of 26 Old 01-29-2010, 05:13 PM
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Re: Blinking Parking Brake Light

watch the brake light...it will blink like it is doing now, count the # of blinks and that is the code...H is on the bottom row and starting from the left, it is the second one...
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post #8 of 26 Old 01-29-2010, 05:14 PM
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Re: Blinking Parking Brake Light

PROCEDURE:
Diagnostic Trouble Codes (DTC) 's can be displayed by jumping terminals "A" and "H" of the Data Link Connector and observing the flashing of the "BRAKE" warning light. This should only be done when the brake lamp is "ON".
The terminals must be jumped for about 20 seconds before the code will begin to flash. Count the number of short flashes starting from the long flash. Include the long flash as a count. Sometimes the first count sequence will be short. However, subsequent flashes will be accurate. If there is more than one failure, only the first recognized code will be retained and flashed.
NOTES:
DTC's 6, 9 and 10 will only turn the "BRAKE" lamp on while the fault exists. These are soft codes faults and can only be read with the Tech 1 scan tool.
Do not jump terminals "A" to "H" if the "BRAKE" lamp is not on. Jumping the terminals with the "BRAKE" lamp off will set a false DTC 9. This will turn the "BRAKE" lamp on and disable the antilock system.
  • 1, 11, & 12 ECU Malfunction
  • 2 Open Isolation Valve or Malfunctioning ECU
  • 3 Open Dump Valve or ECU Malfunction
  • 4 Grounded Antilock Valve Reset Switch
  • 5 Eccessive Actuations of the Dump Valve
  • 6 Erratic Speed Signal
  • 7 Shorted Isolation Valve or Faulty ECU
  • 8 Shorted Dump Valve or Faulty ECU
  • 9 Open Circuit to Speed Signal
  • 10 Brake Lamp Switch Circuit
  • 13, 14 and 15 ECU Malfunction
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post #9 of 26 Old 01-29-2010, 05:28 PM Thread Starter
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Re: Blinking Parking Brake Light

I went through that procedure and it gave me four short blinks then a long blink, four short blinks then a long blink, and on

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #10 of 26 Old 01-29-2010, 05:41 PM
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Re: Blinking Parking Brake Light

Then I suppose that would be code 5, excessive acctuations of the dump valve.....
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post #11 of 26 Old 01-29-2010, 05:44 PM Thread Starter
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Re: Blinking Parking Brake Light

And what exactly does that mean, and how do I fix it? It just started blinking and I haven't noticed any differences in driving or stopping.

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #12 of 26 Old 01-29-2010, 05:45 PM
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Re: Blinking Parking Brake Light

honestly man, like I said above...the RWAL is useless...I would disconnect the module and ride...
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post #13 of 26 Old 01-29-2010, 05:50 PM Thread Starter
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Re: Blinking Parking Brake Light

What does it look like? Where is it in relation to the fuse panel?

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #14 of 26 Old 01-29-2010, 05:53 PM
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Re: Blinking Parking Brake Light

under the hood next to the master cylinder, there will be a black box, should have two (IIRC) connectore plugged into it....

I have been running mine unplugged for a couple years now...and you will find a lot of guys on here foing the same.
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post #15 of 26 Old 01-29-2010, 05:55 PM Thread Starter
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Re: Blinking Parking Brake Light

How is your fuel mileage? It doesn't have any ill-effects?

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #16 of 26 Old 01-29-2010, 06:16 PM
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Re: Blinking Parking Brake Light

it doesnt affect fuel mileage at all...all that box is is like the brain for your RWAL...
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post #17 of 26 Old 01-29-2010, 09:54 PM
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Re: Blinking Parking Brake Light

Yep, you have a code 5. My service manual right off the bat says to replace the valve assembly.
As stated before, RWAL is a waste, I mean ya it's OK if you lock up the rear wheels and they try to pass the front wheels, but generally in a panic stop the fronts wheels are what you still want to be able to control. SO yes the rear wheels will lose traction first because of inertia, but again you can steer into the skid, unless your fronts are locked up because you don't have all wheel ABS.
So in short, just unplug the module, unless you live in a state where you get tested for inspection every year and they require the ABS unit to function, then you will need to replace some parts.


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post #18 of 26 Old 01-30-2010, 11:36 PM Thread Starter
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Re: Blinking Parking Brake Light

So I can just unplug the black module next to the master cylinder and trace the wires back to the originating location and take it all of/out and be perfectly fine?

Trail Rig: 91 s-10 Blazer two door. torsion bars and shackles, "modified fenders" to clear 33s.
Daily Driver: 01 Suburban 2500. Pretty much stock for now...
Sold, trying to get back: Beater 89 S-10, 3.4 swap, modified 4wd, custom shortened flatbed, homemade bumpers
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post #19 of 26 Old 01-31-2010, 04:50 AM
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Re: Blinking Parking Brake Light

For insurance purposes, I would leave it in there...just incase you need to hook it back up for something...
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post #20 of 26 Old 02-16-2010, 09:27 PM
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Re: Blinking Parking Brake Light

hey guys not to thread jack but this is the only thread i found with a similar problem. my parking brake light blinks for 6 short 1 long, its a 91 4.3l as far as i know this truck never had abs. any ideas? and sorry to jack

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post #21 of 26 Old 02-16-2010, 09:31 PM
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Re: Blinking Parking Brake Light

7 Shorted Isolation Valve or Faulty ECU...

You really dont have "ABS"...it is just RWAL and it was standard in all S Series trucks starting in 1989
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post #22 of 26 Old 02-16-2010, 09:32 PM
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Re: Blinking Parking Brake Light

Did you jump A & H?
I do not know if they all had RWAL or not, but you will see a module next to the master cylinder, it sits sideway with two connectors on it, if you have this then that is the easiest way for me to tell you that yes you have RWAL.
Please respond back.


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post #23 of 26 Old 02-16-2010, 11:14 PM
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Re: Blinking Parking Brake Light

yes i do have that unit, i always wondered what that was. and from the above posts there are no ill effects from removing it. thank you for the info .

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post #24 of 26 Old 03-16-2010, 07:05 PM
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Re: Blinking Parking Brake Light

Sorry to Jack the thread also. Have a code six. Five short and one long. It says "erratic Speed signal. How can this be fixed?
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post #25 of 26 Old 01-02-2016, 06:07 PM
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Re: Blinking Parking Brake Light

So, I have an 11 code. ECU malfunction. Which ECU? The main computer or the one next to the master cylinder?
It started tossing the code, acting like it was missing a few times and the started spark knocking very bad,would die as soon as I turned on lights or hit the brakes. Needless to say,a fun ride home.

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post #26 of 26 Old 03-01-2016, 03:48 PM
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Re: Blinking Parking Brake Light

Quote:
Originally Posted by alderfek View Post
So, I have an 11 code. ECU malfunction. Which ECU? The main computer or the one next to the master cylinder?
It started tossing the code, acting like it was missing a few times and the started spark knocking very bad,would die as soon as I turned on lights or hit the brakes. Needless to say,a fun ride home.
The one next to the master cylinder. Black plastic box 6 inches square, inch thick. Two wiring plugs facing rear. Rear wheel antilock brake computer comes standard on 1989 S10. In a fault the brake light comes on and stays on. If it's blinking it's stuck in the code reading mode. You can reset code reading mode by removing the fuse labeled "Brake" for 5 seconds.

You can read the codes by shorting A and H together on the ALDL connector with a paper clip. A is upper row far right. H lower row, second in from the left. Short those, turn the key on, and it starts blinking the code. Once in that mode it stays that way forever until you remove the brake fuse for 5 seconds. Haynes manual doesn't say it will stay blinking. Removing the fuse clears the trouble codes.

Mine was a code 7 faulty isolation or control unit. I checked the isolation valve by disconnecting it (tan/white wire going to front/rear proportioning valve right below master cylinder". Light should go off when unplugged from the switch. It didn't for me. So it appears to be the control unit.

Everyone says the RWAL is just about useless, which it probably is. So I simply disconnected the top connector from the controller, taped the openings to keep out water and dirt. Light went out. Brakes still work. Now the brake light is just a parking brake warning light. Legal requirement in Texas is that parking brake light works when pedal is depressed and no dash warning lights are lit. RWAL doesn't have to work but it will fail inspection if the warning light stays on.
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