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I've had my mobile setup for several years. A Galaxy 979-DX, driving a 2-pill amp, with a 102" stainless whip mounted on the passenger's side rear sidewall of the bed of the pickup. I'm using "standard" off the shelf thin coax (18'). This is all setup in a 2007 Toyota Tacoma.

Over the last several weeks, I've attempted to replace the 2-pill amp with (3) different 4-pill amps and continue to get the same problem, which is intermittent activation of the ABS light, which turns-off the anti-lock brakes. I've never had this problem while using several different brands of 2-pill amps. I've tried a 4-pill RM Italy amp, a 4-pill Palomar and now a 4-pill Texas Star. They all will intermittently turn the ABS light on.

In each case, I've had the amp grounded to the frame. I even ran another ground from the shielded side of the coax (at the antenna mount) to the wheel well. I still have the problem.

Some of the locals have speculated that I may have stray RF through the coax which may be activating the sensor. I have off-the-shelf type thin coax, meaning nothing top-end or high-quality. My question is, do you think it could be coax related? If I upgraded to a better coax, would I have a good chance of fixing the problem? If I were to upgrade, what do you suggest? I'd like the coax to stay as thin and pliable as possible an still be able to correct the problem. Power wise, the amp is dead-keying about 120-watts and swinging to 475 or so.

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"... it's not what you take when you leave this world behind you, it's what you leave behind you when you go."

this_is_nascar,
Is this problem coax related? No, it isn't. It's related to RF getting to the sensor, that's true, but 'bad coax' just isn't where to fix that unless the coax really is bad (doubt it), cuz there's much more RF being delivered to that sensor just coming from the antenna via the cable going to that sensor. Suppressing any stray RF going into the vehicle's computer via that sensor's line is a good idea. Doing the same suppressing to ALL the lines going into that computer is even a better idea, just don't ask me how, I honestly don't know. Sounds like another good reason for that 5 gallon bucket of torroids, doesn't it? If that sensor is a DC device, then by-passing it with a capacitor would/should work. Not knowing if it is a DC device, I certainly will -NOT- tell you to do that! (Completely 'off topic', I hate ABS! It's gotten me into more 'situations' just being there than I've ever had when it wasn't there. If I could figure out how to not have that dash light come on, I'd disconnect the ABS. That's another one of those "I ain't telling you to do that!" thingys.)
One solution is to reroute that feed line so that it doesn't come close to the sensor or computer. "Sure cure"? Nope, but something to try. (Or route the feed line through a metal conduit? Car manufacturers used to do that for 'service' vehicles, you know.)
Good luck.
- 'Doc

Isn't it odd that news cars with all of the engineering that goes into them can't keep out RF. But when a little too much RF is in the system, it exceeds what they were designed for. Now, it's a cryin shame that the RF present doesn't mess with the 2 pill setup, and won't work on any 4 pill setup. Surely, the steel whip is the best that anyone can do for an antenna - it's ideal. Maybe you just hit the wall with the RF limit? If you put some shielding around the feed harnees and ground it, as well as the torroid treatment on everything - it might end up working. I hope all of your effort pays off and works. But if it doesn't; then you may well have to accept the limits of what that vehicle can handle. We will be waiting to hear what happens after you change out the coax and shield it all.
Pictures would be nice - too.

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What gear do I use?
BASE: Icom IC-718 & GAP Titan DX, Yaesu FT-8800R & Diamond X50A, Magnum OmegaForce S45 & IMAX 2000 w/Astatic D104/TUP9.
MOBILE: Galaxy DX99V & Wilson 1000 w/Astatic D104-M2, Yaesu FT-8800R & Diamond NR-770.
"...WR-11 San Jose CA - Standing By..."

You may also be getting stray RF on the amplifier power lines and that power line happens to run near the ABS circuit on it's way to the battery. You can try adding a/some bypass caps near the amp to see if that helps. Make sure whatever cap you use can handle the current rating you need.

You can also try grounding the amp better right where it's installed. What size ground strap/wire are you using to the frame. Make sure the frame is grounded to the battery also.

I love ABS, one of the better things they have come up with. Very good for young drivers and winter driving.

Nascar, try plopping a Wilson mag mount on the roof and see of the problem goes away. Also, 95% or better sheilded coax should be fine.

yea i agree with rob,.these nnewer vehicles can be a pain when it comes
to radio gear.i honestly dont know if changing coax will help.i do know
poor shielded coax can cause ya headaches.could try times lmr240
its double shielded.maybe try flat grounding wire as opposed to braided
wire for grounding.just suggestions here

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skythumper65dx

As well as the suggestions provided, have you thought about using a bandpass/low pass filter after the amp? When i used to go mobile, i used to set car alarms/house alarms off regularly using just a 30 watt amp. When a filter was fitted, problems reduced by over 75%. Good luck mate.

Tinfoil on the ECU might help, I've heard.

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XDX74