Toyota Nation Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Long time lurker, 1st time poster. I have an '05 access cab prerunner and noticed today that my tachometer has stopped working. I also notice that the gas and temp gauges don't start working for 5-10 seconds after I start the engine. I haven't done any mods or anything at all with the wiring.

I searched and didn't find anything related, has anyone had this problem or can anyone give me an idea of what might have happened??

Thanks!
 

·
Registered
2007 Tacoma DC Sport
Joined
·
504 Posts
:welcome:

That's really weird. That has never happened to me...

Take it to your dealer and see what they can do.
 

·
lover of teh boobies
'05 Tacoma AccessCab
Joined
·
2,547 Posts
Don't let them just fix it though... I'd bet you're out of warranty and that'll probably be an expensive fix. Just ask them to diagnose it.
 

·
Official Baller
'07 Tacoma PreRunner
Joined
·
2,960 Posts
Don't let them just fix it though... I'd bet you're out of warranty and that'll probably be an expensive fix. Just ask them to diagnose it.
Diags are still expensive.

Have you tried unplugging the negative and positive battery terminals and touching them together, wait 5 mins, and reconnect them?
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
I did unhook the negative cable today and let it sit for a while. It didn't help, still the same problem. What's the theory behind touching the positive and negative cables together? Never heard of doing that before.

Any other theories out there?
 

·
Official Baller
'07 Tacoma PreRunner
Joined
·
2,960 Posts
I did unhook the negative cable today and let it sit for a while. It didn't help, still the same problem. What's the theory behind touching the positive and negative cables together? Never heard of doing that before.

Any other theories out there?
Drains the battery quicker.
 

·
Registered
Joined
·
223 Posts
how does touching the negative and positive battery cables drain the battery quicker? the cables would nto be touched to the battery. im i confused or something?
 

·
Registered
Joined
·
495 Posts
Some people claim it will drain power stored within the vehicle electrical system. I have no idea if it does, but I've never done this. Taking the neg. terminal off does the same thing.
 

·
Official Baller
'07 Tacoma PreRunner
Joined
·
2,960 Posts
how does touching the negative and positive battery cables drain the battery quicker? the cables would nto be touched to the battery. im i confused or something?
EDIT: I meant drain the car.
 

·
Registered
Joined
·
223 Posts
ok. i can understand more that putting the positive and negative cables together will drain the car. but could you also just take the cables off and turn the key to the on position and do the same thing?
 

·
Registered
Joined
·
11 Posts
Discussion Starter #14
OK guys and gals, I have to give this thread a bump. Since I last posted I've noticed that the tach has started working sometimes, and that the gas and temp gauges also seem to be working intermittently. No pattern, just sometimes when I start it up it all works fine and other times not. The tach has only worked a couple of times, and the gas and temp gauge have only NOT worked a couple of times, although they both (temp and gas) are slow to kick in when I start the engine.

My guess is maybe a loose wire or connection somewhere but I don't really know where to start looking. Any ideas/thoughts from some of you electrical gurus out there??
 

·
Premium Member
Joined
·
2,629 Posts
Based on 2006, which is what I know a little better.

The Combination Meter houses your tachometer control, temp control, and the low fuel light. Your fuel gauge seems to be an external device (f19),

The Engine Control module feeds the tach and the temp gauge

The 7.5A gauge fuse feeds the tach and temp pieces of the combo meter, as does the 7.5A ECU-B fuse.

The 7.5A gauge fuse also feeds the gas gauge, and various idiot lights. Do all your idiot lights illuminate when you power up the truck? If so, that reduces the possibility of / eliminates that one.

The ECU-B feeds tons of stuff according to the Overall Wiring Diagram, the body ECU (multiple times), not sure what all else right now

I can't imagine the truck going far without that one (your interior lights may not work, how could you see to put the key in the ignition)

Use these as ideas to track down your source. Figure out what works and what doesn't. May be a wacked fuse, but more likely an intermittent connection. You close enough to water to have lots of rust problems?

And the reason the truck is important is they use slightly different wiring diagrams, depending on I4 v V6, 4wd, etc etc etc, all add more wiring diagrams to look at. Also, knowing the year tells me how relevant the wiring diagrams I'm looking at are.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #19
I think the intermittent connection is more likely, everything else is working OK. No rust problems either. I'll have to just try to take a good look at the connections when my days off roll around. Don't want to take it to the dealership as I know they'll charge an arm and a leg for what is probably a simple fix.

Thanks for the reply.
 

·
Registered
06 Taco 4x4 TRD
Joined
·
796 Posts
RTFM has some good information. I'll add a few thoughts.

The tach and temp info comes from the ECM, and also talk to the AC amplifier and OBD port, so they have that in common. But the fuel gauge talks only to the pump/sender back in the tank and has nothing in common with the tack and temp gauge. No common connectors or junction boxes or anything. And it's a very simple circuit. So I would conclude that the problem lies in the combination gauge itself, or its connectors. Interestingly, wires from sources for tach, temp and fuel are right next to each other in the bigger of the two gauge connectors, the 40-mer, at 7, 8 and 9. So maybe that's something to look at.

If you remove the lower and upper halves of the left side dash, which is not too hard, you'll be able to access the combination gauge panel. Four screws and it's out, and you can look at the connectors, and maybe the wiring harness that contains all three wires and goes down toward the left kick panel, I think.

Other than that, info inside the combination gauge itself is very sketchy, but I'd bet the circuits for the three gauges diverge pretty quickly, so it seems if the trouble with the three are related, it has to be in the connector, the harness, or just inside the gauge assembly itself.

Hope that helps your thinking a little. Good luck. These things can be tough sometimes.
 
1 - 20 of 25 Posts
Top