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Duncan
Dodge Dakota
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8/30/2004
10:11:26
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 Subject: anti-lock problems
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Message:
Has anybody had a problem with inconsistent braking on their Dakota’s? My rear wheel anti-lock brakes kick in even during normal braking situations and the truck lunges forward requiring additional pedal pressure. This is intermittent, so you never know how the truck is going to react, until you hit the brakes. On two occasions the brake pedal has gone just about to the floor, and the brakes were almost non-existent. The two times this has happened, letting up on the pedal and re-applying the brakes didn’t make a difference. I plan on taking it to the dealer, but since it is intermittent, I don’t hold up much hope that they can find the problem. Has anybody else had this problem, so I can give more information to the dealer?
Thanks, Duncan
2002, Dodge Dakota QC, SLT+, 4.7 L, rear wheel anti-lock brakes, completely stock.
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Webtiger
GenIII
8/30/2004
17:38:38
|  RE: anti-lock problems
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I haven't had the problem you described but a piece of advice for your dealer visit.
If they say can't repro the problem and/or no codes appear on scan then you need to take the Service Advisor/Writer on a test drive and recreate the problem and also insist that they pull the complete code history from the PCM. I'll bet that doing both will pretty much prove you've got a problem.
Ken Grierson
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Noltz
Dodge Dakota
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8/31/2004
10:16:26
| RE: anti-lock problems
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Problem is if the anti-lock is functioning, regardless of how poorly, the ABS computer will not trip a code. Pulling a full history will not help here, only recreating the problem can.
Antilock only knows how fast the car is going by watching a spinning rings that excites a sensor usually on the rear axle hubs, (or on the driveshaft for the rear,) and the front brake rotors. When it sees the fronts are still moving but the rears have stopped, it blocks pressure from your foot and releases the back brakes. Once the rears are rolling again, it allows more pressure from your foot to the backs, until again they lock. It repeats about 10 times per second.
If those metal exciter rings get dirty, or worse cracked, the input signal goes from a nice clean sine wave to an erratic, jerky signal. The computer, having no common sense, thinks the wheels have gone from 55 mph to zero, then up to 200, to 25, down to zero, and straight to hell. It tries to apply and release the brakes to control what it thinks is a lock-up condition, when it is in fact just defective sensors or rings.
For diagnosing, the mechanic will need to have a second person in the vehicle. While guy #1 is driving, #2 watches the wheel speed sensors on his scan-tool. Scanners can watch the exact speed of each wheel. The one thats dropping out or erratic in a straight line, is the problem.
If they can't find a problem;
(.... they really suck, but....)
You don't want to hear this, but you're best to leave the truck at the dealer for a few days. Tell the service advisor you want the mechanic to take it home, so he can drive it for a good half hour or whatever, and feel the problem. Tell them you don't feel safe in it, since the brake pedal as dropped out from under you twice. You'll give them a call back around 9 the next morning & find out what's up. Being reasonable is the best way to get good service from a dealer.
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Duncan
Dodge Dakota
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9/02/2004
10:03:06
| RE: anti-lock problems
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Thank you very much Webtiger and Noltz for your good input. I’ll be taking it in next week, and will use your advice. I want to make sure they get it fixed.
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