Mechanics

QUESTION BRAKE PEDAL TRAVEL

2001 Isuzu Rodeo

Brakes problem
2001 Isuzu Rodeo Question 6 cyl Four Wheel Drive Automatic 210, 00 miles

This Rodeo has 4 wheel ABS. Sometimes while stopping, the pedal will go to the floor. Then I pump the pedal and the wheels lock up and stops very quickly. After that, everything acts normally for a while and it will do it again.

I cannot get it to repeat itself in the presence of a mechanic. Hard to troubleshoot when it won't fail all the time. Thanks for any help.
Avatar
Huladick
July 13, 2008.




Any dash lights come on when it happens?

Merlin2021
Jul 13, 2008.
No dash lights. Just the pedal going to the floor.

Tiny
Huladick
Jul 13, 2008.
The combination valve may be defective if the dash light didn't come on during the problem. If this is bad pressures between front and rear is affected, and pedal hieghts will change until the valve centers.

Merlin2021
Jul 14, 2008.
Thanks Merlin.

If the combination valve was bad, would I still feel brakes at either front or rear? When my problem happens, I have no brakes at all until I pump it. Then they lock up.

Tiny
Huladick
Jul 14, 2008.
If the combination valve is bad, we can test it! Open a bleeder at the rear and have a friend turn the key on wait until the warning light goes out, open bleeder, push pedal down slowly and hold, close the bleeder, did the warning light go on? Then repeat this test at a front bleeder, if thelight does not go on, valve is bad! The other possibilty is contaminated fluid, if tranny or motor oil was added to the master cylinder, you will also have these problems, and it will get worse until all parts made of rubber are replaced, oil swells the seals and softens them. Test the fluid by removing some from the master and putting it in a cup of water. Swirl it, the color should turn milky white, with NO OIL beads in it.

Merlin2021
Jul 14, 2008.
Correction: It has ABS light coming on when this happens. EGR valve is bad/going bad, Could this have anything to do with it?

Tiny
Cagriff2
Aug 7, 2008.
Not likly that the EGR has anything to do with it. Read the codes like this...post em and we go from there. OK" ANTI-LOCK -2001 Isuzu Rodeo LS
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RETRIEVING DIAGNOSTIC TROUBLE CODES

Using Scan Tool
Connect scan tool to Data Link Connector (DLC). See Fig. 1 . Following scan tool manufacturer's instructions, select appropriate mode to view DTCs. If DTCs retrieved, see DIAGNOSTIC TROUBLE CODE INDEX table. Identify DTC and perform specified diagnostic procedure. See DIAGNOSTIC
TESTS . After repairs, DTCs must be cleared. See CLEARING DIAGNOSTIC TROUBLE CODES . If no DTCs are retrieved, diagnose by symptom. See SYSTEM TESTS .

Using ABS Warning Light
1.When ABS warning light remains illuminated, EHCU will store DTCs and disable ABS system. If DTCs are not displayed, wiring harness from EHCU to ABS warning light may be disconnected. Check and repair harness if necessary. 2.Ensure ignition is off and brake pedal is released. Using jumper wire, jumper Data Link Connector (DLC) terminals No. 4 and 12. See Fig. 1 . Turn ignition on. DTC is displayed by flashing ABS warning light. See Fig. 2 . 3.A stored DTC is displayed 3 times, each being separated by a 3.2 second pause. If multiple DTCs are set, second DTC will follow after first DTC is displayed a third time. All DTCs contain 2 digits. First digit of DTC is identified by a series of .4 second flashes. After a 1.2 second pause, second digit of DTC will follow in another series of .4 second flashes. If no DTCs have been stored, ABS warning light will repeat DTC 12 (system normal). 4.If DTCs are retrieved, see DIAGNOSTIC TROUBLE CODE INDEX table. Identify DTC and perform specified diagnostic procedure. See DIAGNOSTIC TESTS . After repairs, DTCs must be cleared. See CLEARING DIAGNOSTIC TROUBLE CODES . If no DTCs are retrieved, diagnose by symptom. See SYSTEM TESTS .
Fig. 1: Identifying Data Link Connector Terminals

Fig. 2: ABS Diagnosis Using ABS Warning Light


http://www.2carpros.com/forum/automotive_pictures/62217_ABS_1.jpg


Merlin2021
Aug 8, 2008.
Hi Merlin2021,

I do have a question, the clearing of the codes, it mentions to jumper terminal A to terminal H of the ALDL/DLC. Is that different than what the Pin 4 to Pin 12 for reading the codes?

I have an obd2 scanner but it won't read the ABS codes. The manufacture says the abs update will not work on my rodeo.

Tiny
Jawong71
Nov 24, 2009.
I have found two ways, one is sure to be right.
1. With the ignition off jumper pins 4 &12 of the DLC connector 2. Switch the ignition on & allow the ABS lamp to flash at least once before proceeding. 3. Depress the brake pedal by hand until you hear the solenoid click, then release the pedal.   Repeat   8 times within 3 seconds.   After the 8th pedal cycle the ABS lamp stops flashing, lights for 1 second, then begins flashing code 12 (no codes).   Memory is erased once code 12 flashes 4 times.   Shop key data incorrect & missing important steps to clear fault code. Please revise.
Second way:
Ensure ignition is off and brake pedal is not depressed. Using jumper wire, jumper DLC terminals No. 4 and 12 together, and within 3 seconds, rapidly depress and release brake pedal 6 or more times. See Fig. 1 . DTCs will not be cleared if brake pedal is not depressed within 3 seconds of jumping DLC terminals.


http://www.2carpros.com/forum/automotive_pictures/62217_1_49.jpg


Merlin2021
Nov 25, 2009.
Hi Merlin21,

I finally got around to jumpering the pins. What confuses me is that all reading material says the ABS lamp will flash, but the only lamp that flashes is the AirBag lamp. The code that is returned it 12 assuming that I counted correctly.

But still the ABS lamp on the top of the dash is fully lit. The only thing I can think is that the information here is for a 2001 Rodeo, whereas I have a 1996 model.

I'll try and take a picture to show the dash when I get another chance to work on the vehicle.
AD

Tiny
Jawong71
Dec 2, 2009.

AD