Hi all,
I am new to the forum, just bought an 09 GX470 with 168k on the clock yesterday. It had a great maintenance history with every service done at a dealer, and even taken to the dealer for things like headlight bulb replacement/wiper replacement out of warranty and no major issues. Anyway, i've driven it quite a bit the past two days, and i've noticed a weird behavior when I hit the brakes. Last night i was driving home at night, on a rural highway and had my brights on. If i tapped the brakes, i noticed the headlights would dim slightly. Happened with low beams too. Also, the FM Radio would cut out for a split second sometimes too. Driving around today, headlights off, the same thing happened, and the radio actually randomly rebooted twice, not when I hit the brakes, but after I took off from a stop sign. After a restart of the truck though, it didn't reboot again for a 45 minute drive home with other starts/stops. However I did get the radio cutting out sometimes when I hit the brakes, but not everytime.
It drives fine, it never cuts out and the gauge cluster and other lights don't seem to be effected when driving. When I got home and sat in my garage idling when I hit the brakes I could see my dash lights (like behind the buttons) go dim everytime I tapped the brakes. The battery is pretty new, from Feb 2018 so I don't think it's that, and I don't see anything else going on. It also doesn't happen every single time I hit the brakes if i've been driving around a bit, usually just the first time (like last time it would dim when i hit the brakes the first time but subsequent times when coming to a stop it wouldn't. Same with the radio.)
I've seen other threads mention grounding, and I checked the battery terminals and they seem to look OK, there's a bit of corrosion on the outside of the negative terminal, but I haven't taken the terminal off to investigate the rest.
I"m also concerned about the alternator. I noticed that there are no fender aprons present on the truck, they've all been ripped off and I can see the alternator through the wheel well, and i'm worried that has something to do with it.
Any ideas on where to start?
Edit: I went down just now and turned it to "on" but didn't start it. Turned the lights to "on" (not auto) and tapped the brakes. It dimmed once but then after that it was fine. I tapped the brake multiple times and the radio didn't cut out, or the lights dim. Meanwhile after I got home an hour or so ago, once i parked it and it was idling, and i tapped the brakes, every single time the dash lights were dimming and such. So that's interesting.
Edit 2: Ok so i did another test when it was off. I didn't start it, but did turn it to "On". Turned the brights on, and everytime i tapped the brakes it did dim slightly. Note I did this in a lit garage, so perhaps it was the same magnitude of dim as last night, just wasn't as dark. Anyway I did get the radio to cut out at the same time. The dash lights dimmed ever so slightly at the time. So with the GX not running, and running solely on battery, it seems like it would definitely be a ground issue? Because at that point, the alternator isn't even part of the equation. And the battery is good, and new (and according to inspection from dealer, is fine) so that seems to be about the only thing that makes sense.
I am new to the forum, just bought an 09 GX470 with 168k on the clock yesterday. It had a great maintenance history with every service done at a dealer, and even taken to the dealer for things like headlight bulb replacement/wiper replacement out of warranty and no major issues. Anyway, i've driven it quite a bit the past two days, and i've noticed a weird behavior when I hit the brakes. Last night i was driving home at night, on a rural highway and had my brights on. If i tapped the brakes, i noticed the headlights would dim slightly. Happened with low beams too. Also, the FM Radio would cut out for a split second sometimes too. Driving around today, headlights off, the same thing happened, and the radio actually randomly rebooted twice, not when I hit the brakes, but after I took off from a stop sign. After a restart of the truck though, it didn't reboot again for a 45 minute drive home with other starts/stops. However I did get the radio cutting out sometimes when I hit the brakes, but not everytime.
It drives fine, it never cuts out and the gauge cluster and other lights don't seem to be effected when driving. When I got home and sat in my garage idling when I hit the brakes I could see my dash lights (like behind the buttons) go dim everytime I tapped the brakes. The battery is pretty new, from Feb 2018 so I don't think it's that, and I don't see anything else going on. It also doesn't happen every single time I hit the brakes if i've been driving around a bit, usually just the first time (like last time it would dim when i hit the brakes the first time but subsequent times when coming to a stop it wouldn't. Same with the radio.)
I've seen other threads mention grounding, and I checked the battery terminals and they seem to look OK, there's a bit of corrosion on the outside of the negative terminal, but I haven't taken the terminal off to investigate the rest.
I"m also concerned about the alternator. I noticed that there are no fender aprons present on the truck, they've all been ripped off and I can see the alternator through the wheel well, and i'm worried that has something to do with it.
Any ideas on where to start?
Edit: I went down just now and turned it to "on" but didn't start it. Turned the lights to "on" (not auto) and tapped the brakes. It dimmed once but then after that it was fine. I tapped the brake multiple times and the radio didn't cut out, or the lights dim. Meanwhile after I got home an hour or so ago, once i parked it and it was idling, and i tapped the brakes, every single time the dash lights were dimming and such. So that's interesting.
Edit 2: Ok so i did another test when it was off. I didn't start it, but did turn it to "On". Turned the brights on, and everytime i tapped the brakes it did dim slightly. Note I did this in a lit garage, so perhaps it was the same magnitude of dim as last night, just wasn't as dark. Anyway I did get the radio to cut out at the same time. The dash lights dimmed ever so slightly at the time. So with the GX not running, and running solely on battery, it seems like it would definitely be a ground issue? Because at that point, the alternator isn't even part of the equation. And the battery is good, and new (and according to inspection from dealer, is fine) so that seems to be about the only thing that makes sense.
Last edited:
