VSC TRAC, TRAC OFF is on but ABS is not. What does it means?

Question

I just got a 2002 Toyota Sequoia Limited with 167K miles on it. I've got the VSC TRAC and TRAC OFF lights on in the dashboard but not the ABS light. The mechanic that did my pre-purchase check said that it would go away by itself and that I shouldn't worry.

It got code C1221 meaning: "ABS lamp warning output circuit short to ground. OBD Code C1221: Left Front Wheel Speed Sensor Input Signal is 0" (as of http://www.obd-data.com/c1221.html).

Does this mean that I need to change my left front speed sensor?

Best, Emil

Answer 1

Before replacing the sensor, disconnect it at its plug to the loom. Test for a resistence across its two terminals. The code is telling you of a short to ground. This can mean that the feed wire, the sensor assembly, or the signal wire is not conducting through the circuit. Check the cabling for breaks or damage, especially on its bends. No breaks, or no continuity then simple change the sensor. Your mechanic was perhaps telling you that the brakes will work perfectly with the ABS not working, but they will not have the anti-lock feature on 'panic braking'.

Answer 2

I was having these lights come on and the vehicle would jerk slightly to the left. The VSC OFF button would not toggle them off. If I shut down the Sequoia, then restarted it, the lights would come back on. If I waited 20 minutes before restart, the lights would then go off and would not come on for a while. When the weather got hot I noticed the problem happening more frequently.

An awakening! The problem was heat related. Also, the owner's manual declared that the VSC was only operable in 4wd mode. I was not using 4wd. Took a peek underneath and saw the transfer case actuator was located directly above the exhaust with a smallish heat shield. Tapped into the actuator are 2 mechanical switches similar to many brake light switches. I unhooked and test jumped each and the result was rewarding. Jumping the lead to the forward switch turns on both the VSC OFF and VSC TRAC lights when the key is on. My conclusion is that a heat related short in this switch would not only turn on the lights, but would also confuse the computer as it was somehow out of phase.

Dealer wanted $126.00 for a new switch 84222-12010. I told him where he could put it. He told me he already had a few up there! I then worked my old switch for a while by hammering the sprung ball on the end repeatedly with my fist to see if working it may help. I reinstalled the switch, and so far so good. I can get a switch off ebay for under $70. I believe I'm on the right track and will pay out $70 if the problem comes back and or see if I can fabricate a better heat shield. I do hope this helps you. Felt bad about those giving the dealer over a grand and having the problem recur.