Daily Dash Light Flash

Greetings!

Here is my first post. I have used Tacoma World as a resource for years with my two Tacoma’s and appreciate the wealth of knowledge here. I am usually able to find an answer to my question without posting; but, for my latest question I have been unable to find an answer to and it has flummoxed me.

Here are the details:

Mid July I purchased a stock 2009 Tacoma TRD, 6cyl, 4wd, Auto, Access cab with around 136k miles. I bought it from a local gentleman. He had owned it for about 5 years and drove it during the summers locally to do errands. It sat most of the winter while he travelled south. He told me a few things that it needed (brake caliper, tires). I fixed them and the truck ran well.

What is the problem?

Mid September while camping I started it up one morning and I found an array of dash lights. The Brake and ABS lights were on solid. The Hill Descent, Auto LSD, Traction and Traction Off lights were blinking. I turned the truck off and all of the lights cleared.

This same event continued to occur each morning. A week or so in it seemed that the restart trick no longer cleared the dash lights (I have not tried recently). So rather than restart I started driving the truck and within a minute the lights would clear. Since then the time and distance to the dash lights clearing has increased. It now takes about 4 minutes.

What is happening?

This happens ONCE per day. If I drive the truck all day and start and stop throughout the day the dash lights do not come on. This only happens on the first start. It doesn't matter if that FIRST start is in the morning or evening. If the first start for a new day is at night this still occurs, but still only once each day.

This sequence of events is not dependent on driving the truck. If I start the truck and let it idle in the driveway the dash lights will clear just as they do if I was to drive it.

Weather does not seem to have an effect. This occurs if it is dry or raining. It occurs on warm on cool mornings.

Additional things occurring simultaneously?

When the dash lights are flashing here are other notable symptoms

Speedometer does NOT work

Backup Camera does NOT work

Power Inverter does NOT work

Tachometer DOES work

Windows DO Work

Climate Control, Fan Speeds, Recirculate DO work

Headlights, Fog, Brake and Reverse Lights DO work

Wipers DO work, However they seem to come on only High Speed and are Delayed turning off when I switch them off.

If I engage 4wd Hi (during this event) the 4wd and 4Lo lights start to blink on the dash also and continue to blink once the other lights have cleared. Once everything is clear I can engage 4wd.


What have I checked?

I have visually examined each ABS Sensor at each wheel and its wire. I have not pulled the sensors out of the wheel.

I have visually looked for loose harness connectors and not noted any.

I have tested the battery and tested it during a start cycle and the battery is good.

Was there a readable code?

My basic OBD scanner did not pick up any codes (more below). I took it to AutoZone thinking it might be an ABS code and there were no saved codes. It seems that once the lights stop flashing everything is cleared.

Twice in the past two months during one of these events the CEL has come on and stayed on after all of the other lights have cleared. This has only happened twice and only when I have driven the truck with the array of lights flashing and without the speedometer working. These two occurrences seem more related to the fact that I have driven the truck without the speedometer working. If I recall the first time this happened correctly I visibly saw the CEL illuminate while driving down the road at my estimate of 45mph.

The Code that was read for these two events was P0500 - Speed Sensor A. If I clear the code it stays clear. This truck pulls it speed reading from one of the wheels ABS Sensors.

Have I done anything else to the truck?

Since purchasing the truck in July I have done the following most of which was done before the dash lights started:

Replaced both front brake calipers

Replaced fluids - Oil. Front/Rear Diff and Transfer Case

Replaced the air filter

Removed, Re-greased and Reinstalled the 4wd actuator

Pulled the Overhead Temp/Compass, tried touching up the solder, reinstalled, but it still did not work so I have left it disconnected. I did however try reconnecting it for a period of time and the symptoms above continued.

This past month I had my mechanic replace the Rack and Pinion which had begun to seriously leak.

There it is.

I think I have added all of the details. I am not an electrical engineer. I am not a professional mechanic. I am a handy home mechanic that grew up with a professional mechanic for a father.

What has flummoxed me is that these dash lights are coming on only once each day and clear without any code or intervention. Any suggestions on what it could be or what I could reasonably within my skill level check?

Thanks!

 

https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/


it’s the p0500 for sure @Dm93 made a posting about it and can help you out. Read his diagnosis post and it will help you get started.

the vehicle is losing speed signal, it makes the most sense.

 

I'll have to poke around in some diagrams later but from what your describing I'm thinking your intermittently missing an ignition power feed.

The P0500 is almost certainly an effect of the ABS being offline as vehicle speed signal is supplied to the speedometer (Combination Meter) from the ABS module (Skid Control ECU) and the Combination Meter then sends it out to the other modules that require it.

I'd be more interested in what codes are stored in the ABS module.

Do the reverse lights work when this is occuring?

 

Thank you both.

I will look at 2nd Gen Information & Diagnostics post. But it does not feel like an actual P0500 code issue. Why? Because the CEL has only come on with the P0500 code twice out of all of the other times that I have started the truck. I think that this code is being thrown as a result of me driving it without a working speedometer which is a symptom that goes along with the flashing dash lights. Also it would not really explain why when I start the truck throughout the day and have no flashing dash lights or CEL. This issue is limited to the first start for the day. I am open to looking further into this though.

Of note there is one slight addition that may fit into Dm93's post. When I first start the truck each day it might be helpful to note that I put the key in the ignition and start the truck there are no immediate flashing dash lights. After starting the engine I think there is a one to two second delay before the dash lights start flashing. (sometimes long enough to get my hopes up that the issue has cleared).

I only have a basic OBD reader which does not read ABS codes; however, when I brought it to AutoZone they did not pull any ABS codes or any stored codes. This was of course after driving the truck and having all of the flashing dash lights clear on their own.

 

Yea like I said above I'm pretty sure the P0500 is an effect not a cause.
Check your reverse lights when the problem is occuring, if they don't work that will give us really good direction.

 

Reverse lights do work during these events.

 

But your backup cam does not correct?
Is it in the radio or mirror?

 

That is correct.

Back up lights DO work.
Back up camera does NOT work.

Back up camera is in the mirror.

 

I'm thinking check all the connectors at the Driver's side Junction Box (Fuse Box/ Body ECU) (Left of steering column behind knee bolster) for corrosion and/or burnt pins.
Also check the grounds behind the left and right kick panels for corrosion or being loose.

 

Reference diagrams.

 

Today I checked.

The harnesses into the front of the Junction box looked fine. I pulled each of them out. I did not see any corrosion or burnt wires.

The grounds behind both kick plates looked good as well. No corrosion and they were secure.

Im not sure if it is helpful… but when the flashing lights clear I always know right before because the engine idle increases slightly (maybe 100rpm, but can be seen on the tachometer).

 

Any other suggestions or recommendations?

Thanks

 

Should I try swapping out a speed sensor for a new sensor or swap the current sensors front to rear.

 

With all the problems you have occurring at the same time I still think you have a main power or ground issue.
Have you checked the grounds under the hood?

 

The fact that this happens when sitting still would imply that the speed data is corrupted, pointing to module or canbus and not the sensors. If the reported speed was zero, the system would be happy. If the sensor was throwing garbage to the abs module, you would likely get a discrete code for that. The code is speedo data and that is post calc from the abs module, not raw data. Go to live data on your scanner and see if it will show wheel speed for each wheel.

 

I had a similar issue that the abs and trac control lights would come on and stay on for a time and then turn off randomly. I checked all the sensors etc and couldn't find an issue. I removed the brake light switch at the brake pedal and sprayed the plunger of the switch and lubed it as well as I could. cleaned it and re installed it (took literally 5 minutes) cleared the lights and fixed the issues. Simple solution but worth a try....

 

Thanks for the diagram. I will check them.

 

Thanks for the suggestion. I will try this as well.

 

I found 4 body ground points under the hood. They could be cleaned up but they do not seem to be the culprit.

 

Brake light switch