Power lead to digital dash

does anybody know if the skinny single connector on the 12V battery goes to the dash LED display? thanks

 

Thanks for the reply and link...
Yeah, have the black speedo/mileo, gaso display problem, used to happen when i charged up the pba battery and turned the car on with it at 14v (more than once, but always when near 14v)...i swapped out the pba since it did a bad job managing the AGM, went lithium iron instead, and presto, black dash problem is back. So i figured if i can set the display to 12v since it started up no problem with that..and it didn't care going up to 14v after the car was on. Looks like i need to find the fuse for that so i can try to dumb start it from there, maybe a few diodes in series with the fuse would wake it back up...i read a few posts about caps on its board, but since I've repeated the blackout senario too many times, i'll spin my wheels down this path to see where it leads...

 

Forgot to add, no codes..at least nothing newer than my ongoing fuel-too-rich one...I checked a few fuses, someone mentioned a panel 7.5A, and gauges 10A. Either side of the 'panel' fuse socket wasn't powered so I pulled the gauges fuse to find which side was, added a rheostat to the other and restarted the car, cranked it to its Rmax (10 ohms) and had 12v on my meter but no display yet.. I'll start out tomorrow and see if the display will start up cold at 12v..I can't remember how i reset it in the past, after i charged the 12v battery at 14.2v and it blanked the cluster, thinking it was the large power connector i pulled and replaced with the car off and got it back...

 

Yeah no speedo and fuel gauges is a big pain...Torque app doesn't access fuel so that was a worry...Had to run GPS speed since the speed dial didn't work right (probably from the speedo being out)...

And some Good news! well, for me anyways.... I disconnected my lithium 12v battery and reconnected my weak 12v lead brick with jumper cables, first press of the start button, click, click, the speedo lights up...

Now for the harder question...anybody have a dash fuse block wiring diagram? If i can choke off some voltage to the correct fuse locations i can isolate the one line that's picky... (thanks in advance)

Likely, there's more than a single 12v wire (and maybe fuse) feeding the speedo panel...some clicks from the hatch area that didn't click with the lithium, kinda tells me something else is routing power to the fuse block/speedo or simply, not routing to the speedo panel...unless its very near 12v... seems like being above 13v is a bad thing when starting up...

In case someone is thinking of going the lithium 12v route, i would wait a tad longer until this is sorted out....lol

 

Found a 2004 wiring diagram, will work with that...

 

Plastics and I never get along...Something always gets cracked or broken even if i tap it with a hammer...lol
Worked a bit on it today, confirmed by other posts and my eyeball the door open blinky is the gatekeeper for this problem. When its gone, the dash doesn't work. With the car off, I pulled each fuse (under the dash) one by one and it never went out, which was odd. Went back to my dying 12v lead brick so i can have my gauges back. Tried looking more for the 2006 manual, got close, but no luck. if i can find the phantom wire for the dash i should be able give it 12v and it would be happy with a 13.4v lithium battery...

 

Thanks for the link, more work to do...lol

 

Ok Gents & Gals, with a 6A dual diode in series with fuse #17 (15A Dome), I made my first trip to / from the gas station using a 12V LiFePO4 battery! The key to this was the door open light was coincidentally on (good) or off (bad) giving the clue that it had something to do with the speedo cluster since it went missing when the dash stopped working. Some of the speedo pics seem to point at this as the first in line on getting things up and running. Trying the diode setup on a few under dash fuses didn't work. The 2 series diodes drop enough voltage when the car is running (nets 12.5V to Dome circuit) so that it thinks everything is good, and works. The relief (for now) is not taking apart my dash...a small celebration...lol
I'll need to waterproof the setup since its not in the fusebox at the moment...
Some background, and beef with all this, since the engine doesn't start with the 12v battery, it should last much longer, like 10-12yrs...my Y/T optima died at 3 years and a few months, which was completely unacceptable...putting in another 15lb floody wasn't the solution either. I think the clue with the early death of the lead battery was measuring 13.8V at 34F, its only at a float charge, it needs to be "charged" (14.5ish) now and then to keep the cells balanced, and likely is how mine died. I opted for 4 x 25Ah cells in series and made my own 12v battery. Zener diodes on each cell offer some balancing when full. Lithium doesn't have a float constraint, its just relates to the capacity of the battery (SOC).
If it all goes south, I'll be sure to provide followup info...

 

I want to thank the group for the help in resolving this problem with using a lithium 12v battery and essentially fixing the speedometer / fuel / odometer (dashboard) out phenomenon. The door open light greeted me when I checked on it this morning, temps dipped to 40F.

 

So instead of rolling your own 4 cell lithium battery like i did, you might want to explore this option..
Amazon: 12V 36Ah Deep Cycle LiFePO4 Battery, 2000 Cycles Miady Rechargeable Battery for Golf Cart, Boat, Solar System, UPS and More (12V 36Ah)

Dimensions would need to be compared, looks like this option is a bit wider than stock at the clamp but I think there's room in the tray. It has a built in BMS so no worries about getting that setup and working correctly...

I think the + side terminal might need some minor work like I did to attach it to the battery terminal correctly, but at over half the price and better reliability, its a win/win.

Here's the sucky one i had and with its stellar warranty reviews, add mine to the list.
Amazon: Optima 8171-767 DS46B24R Yellow Top Prius Battery

Here's my feeble attempt for a 12V 4 cell LiFePO4 replacement. I just removed the lead terminals and went direct. Some easy cuts on a 2x4 to tighten up the space, takes care of the LxW dimension gap, and a little bendy on the + side, gave me easy access to pull the connectors if I need to remove them...


I still have to install the diode a bit better for the upcoming rain...but I would use this over mine with a higher current rating... Amazon: BOJACK KBPC2504 25A 400V Bridge Rectifier Diodes Axial KBPC2504 25 Amp 400 Volt Full Wave Electronic Silicon Diodes

Wiring that up, the (-) terminal goes to the fuse socket (fender side) and the (+) terminal goes to the fuse socket (engine side) for the Dome fuse #17, the other 2 AC terminals are not used and can be covered. I used some male 0.250" terminals and shaved them to match the width of the fuse blades, shrink tubed the crimps and stuck them in where the fuse was.
After a brief search I got this ordered.. remember add a fuse in series somewhere in that line...this gets you in and out of the fuse box. Amazon: General Technologies Corp GTC062 GTC06X Fuse Socket Connector Kit (LPM style)

 

not sure how to post links, even using the link tool they broke with [media amazon... thought they would copy/paste like the picture...lol