Dashboard lights, ABS, SRS, trac Control….

Hi all;

my buggy is in the shop ( local dealer) with a perplexing problem that may end up costing fair coin just to diagnose.

2015 TRD Sport (Canada eh) with 104,500 kms on it.
V6 auto

The tach, and temp gauges don’t work, the ABS light, traction Control light, check engine light, and SRS light are all on.The Speedo does work…

the dealer has tried clearing the codes (P0500 code) without success, and tried a swapped out gauge cluster as well to no effect..

ive searched here before and found a few similar issues - but not as profound.

this came on suddenly - all issues at the same time.

any ideas?

 

I had a stick fly up and pull one of the wires out of a wheel speed sensor connector once, almost every light went on instantly (due to ABS being disabled).. but did not effect any gauges that I remember.


My money is on that especially since a P0500 is a wheel speed sensor code. Really surprised they aren't chasing that first...

 

jwarr;

Thanks for your response. I was told they did look into this when they tried to clear the codes. I did get a bit worried when they went straight to considering the gauge cluster. - their rational was linked to the srs light which isn’t related to the speed sensor.

 

Sounds like the main wiring harness should be inspected for rodent chewing through

 

Have they checked all the fuses and verified they have power? Powers and ground to the cluster? Codes in other modules?

The fact that the speedometer works but you have a P0500 tells me that the cluster is getting a vehicle speed signal from the ABS module but is either not sending it out or the SPD line has a problem.

 

I’ll be the first to admit that it’s a bit bewildering. I’m more accustomed to the marine industry which is a ways behind the automotive industry in terms of computerization. the fact that the ABS and traction control lights are on - the reason for the P0500 code (?) and the Speedo works mystifies me.

there are no other codes and the tech has said that he hasn’t seen any visual signs or causes.

 

It's because the cluster gets the speed signal first, then sends the signal to the ECM.
Therefor the cluster can work independently of the ECM.
The ECM can get a "bad" signal but the speedometer will still work.

 

Thank you TnShooter;

I appreciate your response - everyone’s responses…

Is this circuit logic is the same for both manual and auto transmissions? (Mine is auto).

Will skid control/abs codes be triggered thru the skid control ecu, or the ecm?
How would this result in a srs trouble light too?

 

The vehicle speed circuit operates the same on auto and manual on 12-15 models, I went into detail on the vehicle speed circuit in the post below.
https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042157

I mean a code in the PCM will also turn on the TracOff light but the ABS and SRS are separate systems, as I said above I'd first want to verify fuses then powers and grounds.

Scan data for each module should show if the lights are being commanded on, if they are then you have to determine why they are. A competent tech that is capable of thinking outside of flow charts should not have a big problem tracking this down.

 

DM;

thanks for your response. I’ll take notes and ask the tech!

 

So it looks like a critter has been chewing on wires….
The dealer phoned moments ago and found it.

Where’s Elmer Fudd when you need him!

thank you to all who responded with suggestions.

 

Glad they found it before the parts cannon was fired.

Now hopefully they will fix the harness and not try to sell you a new one.