Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 2011 Toyota Venza V6 2 wheel drive.
It has developed the following (appears to be) electrical problem...
When the car sits in the sun and the ambient temperature gets over say 78 or 80 degrees...
I push the ignition button and the dash and it's gauges light up temporarily and then everything on the dash goes dead. I don't think it's even getting to the point where the starter is powered up. This problem happens say 1-2 times and then does not happen. I can start the car on say the 2nd or 3rd try every time it occurs. It only happens when the ambient temperature is about 78 degrees and when the car has been sitting in the sun. Further, once I go through one of these bad starting events and it starts up, it starts up every time after that. It's very odd.
I have replaced the starter relay, and an ignition relay in the engine compartment. The battery is new as of about 7 months ago. Also the fuel pump was replaced about 6 months ago. The mechanic said it was not delivering enough fuel pressure to the rail which was causing the problem. I got the car home and the intermittent starting issue still persists. To be more detailed about the actual process. Given the start and solenoid work fine on the 2nd or 3rd try that seems unlike the root cause. Any ideas? To me is seems to be maybe the main relay is crapping out due to heat issues. That is my next replacement, but I know scanners motto is don't become a parts cannon, shooting parts at the problem vs solve it via diagnostics.
I should add that it's about 78 degrees or higher, not only at 78 degrees. It's not temperature from a hot engine. it only happens when sitting in the hot sun. After I experience one of those starting episodes the starting is fine, even after the engine has been running. The sequence of events is always when the car has been sitting for some time in the hot sun and not having been run for a while. One it starts it starts fine for the remainder of the day. This all has the appearance of an electrical based issue. But... what if for some reason the fuel pump(which is new and changing it didn't seem to effect the problem) doesn't create the necessary pressure in the rail which then the power now coming from the alternator and moving engine has no fuel and stops. Again the timing of it all seems like it's fairly quick after touching the ignition button that I see the dashboard and gauge's light up briefly following by a no crank, followed by the dashboard gauges and dashboard going dark. All other electrical systems still seem fine during and after.
Even further... I should add I popped in the OBDII reader and tried to start the vehicle. There were no codes. Not sure if my reader just isn't picking up any codes or the car is simply not throwing any.
More information... The vehicle has 144,000 miles and has otherwise been a non-problematic vehicle. I'm ruling out the battery because it starts on the 2nd or third time each time I experience this problem in the heat.
update... given it's a heat correlated problem consider this. Once it starts it disappears... why is that? because the problem originates from INSIDE the passenger compartment. if it was in the engine bay it would get worse when the engine warmed up after driving. It does not. In fact once the car starts the problem doesn't return(until the next time it has been sitting in the sun for a while) because the AC cools the inside of the car. So I did a test. I let my car sit in the hot Florida sun. I took a window AC I have and put that in the car(properly vented of course) and blew the very cold AC air on the drivers area where the electrical components are(fuse box, relax box, ignition button). I brought the temp way down to very cool temp. Guess what. The problem did not occur. So now I have isolated to the the problem to ambient temperature inside the passenger compartment. My next step will be to pull out the IGN relay on that relay box under the dash and to a relay test.
the items inside the vehicle that are soaked in heat and related to the overall ignition process are the following: ignition relay(ignition 1 circuit), brake pedal position sensor, and gear selector position sensor. of course it could be fuse panel or relay blocks themselves... but I'm holding that as a more remote possibility. Again my next step will be to diagnose the IGN 1 circuit relay to see if it's working ok.
Topic Author
