1990 ABS light?
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
1990 ABS light?
hi all
i started my 1990 c4 up the other day, and i noticed the SERVICE ABS light came on!
What causes this light to light up? is it a brake failure on a certain wheel or something else?
Can i just take it to a my local mechanic or does it need to go to a specialist?
i am in Western Australia, and i know of one place that works on these cars! but is it necessary to go there?
Are c4 abs systems any different to other Abs systems?
thanks
i started my 1990 c4 up the other day, and i noticed the SERVICE ABS light came on!
What causes this light to light up? is it a brake failure on a certain wheel or something else?
Can i just take it to a my local mechanic or does it need to go to a specialist?
i am in Western Australia, and i know of one place that works on these cars! but is it necessary to go there?
Are c4 abs systems any different to other Abs systems?
thanks
Tech Contributor
Joined: Aug 2006
Posts: 9,933
Likes: 103
From: Peoria Arizona.. Resident Gold Cylon
Could be a bad abs wheel sensor (all four wheels have them). However start with the basics hows the fluid level in the Master cylinder. Did you change the brake pads recently? Air in the brake system from a improper brake bleed can cause this as well. GC
Last edited by Goldcylon; May 6, 2009 at 09:45 AM.
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
i start it every now and then, but thats all!
i have checked the oil and plugs, and oil looked like new! but will change the plugs soon!
i haven't changed the brake fluid, but will check the M/C next!
when idling i pushed the brake and could hear the left rear brake make a noise(sort of clunk or something), maybe this could be the problem!?
think it needs to go for a check up! wouldn't putting on new disc's and pads!
thanks for you suggestions!
Pro
Joined: Mar 2009
Posts: 639
Likes: 1
From: Brookfield CT NCM#522998
I have only had the car for 1 month and driven it twice, haven't had a chance to drive it lately, put away under a car cover!
i start it every now and then, but thats all!
i have checked the oil and plugs, and oil looked like new! but will change the plugs soon!
i haven't changed the brake fluid, but will check the M/C next!
when idling i pushed the brake and could hear the left rear brake make a noise(sort of clunk or something), maybe this could be the problem!?
think it needs to go for a check up! wouldn't putting on new disc's and pads!
thanks for you suggestions!
i start it every now and then, but thats all!
i have checked the oil and plugs, and oil looked like new! but will change the plugs soon!
i haven't changed the brake fluid, but will check the M/C next!
when idling i pushed the brake and could hear the left rear brake make a noise(sort of clunk or something), maybe this could be the problem!?
think it needs to go for a check up! wouldn't putting on new disc's and pads!
thanks for you suggestions!
Tech Contributor
Joined: Aug 2006
Posts: 9,933
Likes: 103
From: Peoria Arizona.. Resident Gold Cylon
)or the pads are worn down to nothing. Time to pull the wheel and see whats going on. Sounds to me that this is part of the problem
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
i too want to get it out of "fritz" mode lol
actually i don't think there is anything wrong with mine, it just has SERVICE ABS when i turn the key! it goes away when running!
Last edited by Phantom_Vette1; May 6, 2009 at 09:53 AM.
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
Pro
Joined: Feb 2009
Posts: 589
Likes: 1
From: PA
The click you heard could be just one of the pads that was a little corroded and stuck. You said how your car does more sitting than driving. Curious, have you pushed the pedal, heard the click since the first time you heard it?
I had a problem a while back with my Tahoe's ABS dash light staying on. I didn't want to buy new sensors (only 2 in the front). Anyway, I unscrewed each sensor and found the threads corroded. Cleaned them off with a wire brush, put them back in, held my breath and no more dash light staying on. What I cleaned was the sensors grounds, mating surfaces. Maybe this could be you guys problem with the ABS dash light staying on. Worth a look with taking the senors out and checking for that corrosion.
I had a problem a while back with my Tahoe's ABS dash light staying on. I didn't want to buy new sensors (only 2 in the front). Anyway, I unscrewed each sensor and found the threads corroded. Cleaned them off with a wire brush, put them back in, held my breath and no more dash light staying on. What I cleaned was the sensors grounds, mating surfaces. Maybe this could be you guys problem with the ABS dash light staying on. Worth a look with taking the senors out and checking for that corrosion.
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Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
In case you don't have a FSM, ground pin H (bottom row, 2nd from left) to A (top right) on your ALDL. This will flash any codes that are present, in the same manner you use to check for ECM codes.
Post the codes and I'll let you know what area they correspond to.
Post the codes and I'll let you know what area they correspond to.
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
hmmmm doesn't sound good!
the braking in the vette isn't as good as i thought it would be for a sports car! are they usually very good? or just average? maybe the brakes need replacing? will have to check!
it seems like the brake pedal has to be pressed fairly firmly to pull the car up!
i don't even know where the ecu is, passenger side right?
when you say ground the two pins together, you mean just bridge them? not actually supply ground 0V to them?
Pro
Joined: Mar 2009
Posts: 639
Likes: 1
From: Brookfield CT NCM#522998
Perfectly safe, the ALDL is a little 'plug' under under the dash on the drivers side. It is where you pull the codes from, they sell a 'key' to ground the connections to get the codes to flash, but a bent paper clip works just fine for free. The ALDL is standard on just about every GM car.
Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
is this safe to do, i am dumb as to not know what the ALDL is( a certain plug on the ecu?) sorry very new the electrical side of the vette!
i don't even know where the ecu is, passenger side right?
when you say ground the two pins together, you mean just bridge them? not actually supply ground 0V to them?
[/QUOTE]
As Flynn noted above, it is safe to do.
Look under the drivers side dash and you'll see a connector with 12 cavities. The top right will be A. On the bottom row, second from the left, will be H. Bend a paperclip to fit into the connections.
Turn your key to "ON" only. Do not start the car.
The ABS light will flash any codes on the DIC, starting with 12, which is one short flash, pause, and 2 flashes after (a visual Morse code, so to speak). It will do this 3 times and then transition to any stored codes. If present, codes will always cycle 3 times before moving to the next stored code. Once all are displayed, the DIC will flash 12 again to show it is done.
Have a paper and pen ready to write down the codes and post any that show.
i don't even know where the ecu is, passenger side right?
when you say ground the two pins together, you mean just bridge them? not actually supply ground 0V to them?
[/QUOTE]As Flynn noted above, it is safe to do.
Look under the drivers side dash and you'll see a connector with 12 cavities. The top right will be A. On the bottom row, second from the left, will be H. Bend a paperclip to fit into the connections.
Turn your key to "ON" only. Do not start the car.
The ABS light will flash any codes on the DIC, starting with 12, which is one short flash, pause, and 2 flashes after (a visual Morse code, so to speak). It will do this 3 times and then transition to any stored codes. If present, codes will always cycle 3 times before moving to the next stored code. Once all are displayed, the DIC will flash 12 again to show it is done.
Have a paper and pen ready to write down the codes and post any that show.
Race Director
Joined: Dec 2003
Posts: 14,132
Likes: 935
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
The ABS light in my 91 is on,Ive tried to pull the codes and it wont work.Ive got a cheap scanner that states it will pull the codes,tried an expensive scanner and Ive done the paper clip trick,no dice.With the scanner I can get 12 but wont go past there.Ive been told that the system wont store a code,it will only display a code as long as the ABS Service light is on.My problem is sporadic,here today,gone tomorrow.Ive got the FSM,all I want is to pull up the code so I can go to that area and fix it.
Pro
Joined: Mar 2009
Posts: 639
Likes: 1
From: Brookfield CT NCM#522998
The ABS light in my 91 is on,Ive tried to pull the codes and it wont work.Ive got a cheap scanner that states it will pull the codes,tried an expensive scanner and Ive done the paper clip trick,no dice.With the scanner I can get 12 but wont go past there.Ive been told that the system wont store a code,it will only display a code as long as the ABS Service light is on.My problem is sporadic,here today,gone tomorrow.Ive got the FSM,all I want is to pull up the code so I can go to that area and fix it.
