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Blinking Parking Brake Light

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Old 01-24-2010, 09:47 PM   #1
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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.
Old 01-25-2010, 04:06 AM   #2
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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.
Old 01-25-2010, 08:59 PM   #3
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Re: Blinking Parking Brake Light

What is the RWAL?
Old 01-25-2010, 09:44 PM   #4
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Re: Blinking Parking Brake Light

Rear Wheel Anti Lock
Old 01-25-2010, 10:39 PM   #5
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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.
Old 01-29-2010, 04:50 PM   #6
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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?
Old 01-29-2010, 05:13 PM   #7
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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...
Old 01-29-2010, 05:14 PM   #8
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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
Old 01-29-2010, 05:28 PM   #9
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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
Old 01-29-2010, 05:41 PM   #10
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Re: Blinking Parking Brake Light

Then I suppose that would be code 5, excessive acctuations of the dump valve.....
Old 01-29-2010, 05:44 PM   #11
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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.
Old 01-29-2010, 05:45 PM   #12
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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...
Old 01-29-2010, 05:50 PM   #13
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Re: Blinking Parking Brake Light

What does it look like? Where is it in relation to the fuse panel?
Old 01-29-2010, 05:53 PM   #14
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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.
Old 01-29-2010, 05:55 PM   #15
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Re: Blinking Parking Brake Light

How is your fuel mileage? It doesn't have any ill-effects?
Old 01-29-2010, 06:16 PM   #16
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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...
Old 01-29-2010, 09:54 PM   #17
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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.
Old 01-30-2010, 11:36 PM   #18
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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?
Old 01-31-2010, 04:50 AM   #19
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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...
Old 02-16-2010, 09:27 PM   #20
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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
Old 02-16-2010, 09:31 PM   #21
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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
Old 02-16-2010, 09:32 PM   #22
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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.
Old 02-16-2010, 11:14 PM   #23
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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 .
Old 03-16-2010, 07:05 PM   #24
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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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