Car "shuts off" when I hit the brakes. ABS code 21 also

SCSVTSi

Registered User
I have a strange intermittent problem. When I touch the brakes the car "hiccups" just for a split second. I mean the whole car basically shuts off. It never actually dies and I have to pull off the side of the rode or anything like that. It always "comes right back on". Dash lights will does funky things, tach jumps around, just weird stuff. After this happened a couple of time my ABS light came on. Fortunatlely I have a mostly interstate trip home, so I only had to hit the brakes about 3 times to get home. Since the ABS light came on, I checked the ABS codes and have a code 21. I followed a link from a previous post to an ABS troubleshooting page to see what the code 21 is, Main Valve. I disconnect the 2 pin connector to the actuator and checked the ohms per the diagnostic chart on the page and it is in the 2 to 5.5 Ohm range for which it says to check the wiring harness if i am reading it right. I dont have any ABS wiring schematics to see where or if there are any splices to those 2 wires or where they lead to. I suppose the actuator itself could be having the intermittent problem and just because the ohms checked out that one time that doesnt mean it isn't bad. If the ABS assembly were bad, could it pull enough amps for just a split second that the whole electrical system hiccuped? Has anyone else had anything remotely similar happen? At first I thought I may have a bad battery or engine ground, but then realized it was only happening when I hit my brake pedal. I checked the battery and engine ground anyway and they are fine. For what its worth these are the elec parts that are basically new on my car recently (as you can see I am quite the roll with car problems); cam sensor, crank sensor, ignition switch and tumbler, and starter relay. If the brake pedal switch were bad I dont see it causing anything like this. Another weird thing is that my brakes themselves (as far as pedal feel and actually stopping the car go) seem to be working fine. Perhaps its not an ABS problem at all and the ABS light came on simply becuase the power came on and off so quick a couple of times. Who knows. My Firm Ride light started blinking after all of this too, but after is flipped the ride switch a couple of times, the light stopped blinking. Fortunately I have another car to drive to work, so I have some time to fix it. I welcome any ideas.
 
to me it sounds like it could be bad body ground the small wire from the negative batt terminal to the radiator core support , i just ran an extra wire beside the stock one and mine was fixed
 
i had the same exact problem with my cougar about 3 1/2 years ago and it was a bad ground if i remember correctly, but i know it was something i messed with on the battery, i would clean the posts and terminals or put new ones on and that should fix it
 
Hey New guy here, was reading your question and thought I may have some help for you.

You may have a short problem. Is your battery bolted down if not it could be grounding out, or you could have a hot wire (maybe the starter wire) that grounds out when you apply the brakes. Like 90XR7Cougar5spd said it could be a bad ground that shorts out when you apply the breaks. Just some areas I would look at.

My 67 had a problem similar to that but was when I would put my foot all the way on the loud peddle, the throtle linkage would ground out the coil wire. Took me 3 months to fnd it, only found it when the wire welded itself to the linkage lots of smoke little fire not good.

I hope this helps... Joe

1994 SC Auto saved from the crusher Jan 05

1967 Camaro restoring

1996 Boneiville SSEI

1991 Ram 150 parts getter
 
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90XR7Cougar5spd said:
i had the same exact problem with my cougar about 3 1/2 years ago and it was a bad ground if i remember correctly, but i know it was something i messed with on the battery, i would clean the posts and terminals or put new ones on and that should fix it
Yeah pretty much what everyone else said. I had the same thing on my contour. The negative cable wasn’t connected well to the battery and it actually heated up and burned a hole through the battery's case. All I did was clean everything up real well and tighten it properly and it’s worked like a charm.

Hopefully that fixes it, a real easy solution.
 
yea i had an instance once my batt wasnt bolted down and when i would make left turns my pos batt terminal would touch the hood and kill the car , sometimes it would just cut out for a second or 2 .i prob would have never found it but one night everything went dead and i saw smoke coming from under the hood . i opened it right away i thought something was on fire it melted the pos terminal clear off .i wondered what the devil is going on and looked up and saw where it arcing off the hood . i put a new terminal on and made sure it was covered with the rubber and moved batt over toward the fender and bolted it down . im lucky it didnt riun anything else
 
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I had a bad accumulator with the Code 21 Light, change that

I had a bad accumulator with the Code 21 Light, change that. My Ohms were in the correct range also of 2 to 5.5.



SCSVTSi said:
I have a strange intermittent problem. When I touch the brakes the car "hiccups" just for a split second. I mean the whole car basically shuts off. It never actually dies and I have to pull off the side of the rode or anything like that. It always "comes right back on". Dash lights will does funky things, tach jumps around, just weird stuff. After this happened a couple of time my ABS light came on. Fortunatlely I have a mostly interstate trip home, so I only had to hit the brakes about 3 times to get home. Since the ABS light came on, I checked the ABS codes and have a code 21. I followed a link from a previous post to an ABS troubleshooting page to see what the code 21 is, Main Valve. I disconnect the 2 pin connector to the actuator and checked the ohms per the diagnostic chart on the page and it is in the 2 to 5.5 Ohm range for which it says to check the wiring harness if i am reading it right. I dont have any ABS wiring schematics to see where or if there are any splices to those 2 wires or where they lead to. I suppose the actuator itself could be having the intermittent problem and just because the ohms checked out that one time that doesnt mean it isn't bad. If the ABS assembly were bad, could it pull enough amps for just a split second that the whole electrical system hiccuped? Has anyone else had anything remotely similar happen? At first I thought I may have a bad battery or engine ground, but then realized it was only happening when I hit my brake pedal. I checked the battery and engine ground anyway and they are fine. For what its worth these are the elec parts that are basically new on my car recently (as you can see I am quite the roll with car problems); cam sensor, crank sensor, ignition switch and tumbler, and starter relay. If the brake pedal switch were bad I dont see it causing anything like this. Another weird thing is that my brakes themselves (as far as pedal feel and actually stopping the car go) seem to be working fine. Perhaps its not an ABS problem at all and the ABS light came on simply becuase the power came on and off so quick a couple of times. Who knows. My Firm Ride light started blinking after all of this too, but after is flipped the ride switch a couple of times, the light stopped blinking. Fortunately I have another car to drive to work, so I have some time to fix it. I welcome any ideas.
 
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