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Dash doesn't light?

Discussion in 'Generation 1 Prius Discussion' started by ronlewis, Jan 18, 2024.

  1. ronlewis

    ronlewis Active Member

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    I've not seen this one before. I turn the key on and the dash stays dark. Then I try to start, and it fires up, and the dash comes on. Seems normal. I've only started this car one other time - when I drove it home from the auction - and don't recall it doing it then. I had to jump it both times and figured the dead battery was the issue. But put a new battery in today and it still did the same thing. Anyone heard of this, any ideas where to start? The CEL didn't come on, but I've not scanned it for codes.
     
  2. ronlewis

    ronlewis Active Member

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    OK, back on this car. It has been starting the same way as described above - the dash not coming on untiil the engine is started. I've driven it 5m home and today was driving it about 3m to get it painted. Drove fine, after it starts. same black dash before Ready.

    I jumped it the first time I drove it and it charged up enough on the way home to restarts an hour later. It was more than a week before I tried again, and had to jump it again, so I put a new 12v battery in it. The next day, it was dead too. Apparently there's some kind of parasitic drain going on, so I unplugged the cable connector on the positive battery terminal block thinking that would keep it from draining. That other single wire connector was still connected.

    So today's incident - I forgot to disco that connector a couple of nights ago. It started the next day, so I unplugged it and figured it was still good. Today, it started the same way and seemingly drove fine for about 3m, then kinda died, the dash lights flickering on and off. It crept along for about a 100 yards, and after restarting it, repeated that process again before not moving at all. At that point, the dash was still all lit, the READY was lit, and there were no CELs. One would expect the car to move at that point, but it wouldn't, the touch display had grayed out.

    I'm hoping that all this dying stuff is because the 12v is dead. IIRC, it needs to be above 12.1V to operate correctly, so I'm headed back over there with my voltmeter and my OBDII connector. It's not displayed a CEL or any other trouble light, but the dash is also not lit up now that I've turned it off. If it acts as before starting up, I'm not sure the dash will light up or the OBDII to have power. I'll update later.

    If anyone has guidance on tracking down a parasitic battery drain, please reply with links.
     
  3. ronlewis

    ronlewis Active Member

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    Well, definitely battery issues - only 6v and it's done nothing but sit in the car since I bought it a week ago. This car was wrecked in the middle of the passenger side. There's a couple of harnesses running along that rocker panel. Don't think I've done anything to them in the repair, but maybe damaged in the wreck and shorting out? Is there a drawing of the car's wiring harnesses that would tell me what those cable bundles connect to? Or where the entire harness disconnects? Would like to figure out if there's any harnesses that I can disconnect completely to eliminate them from the possible issues.

    I hate electrical systems - know nothing about them and seem incapable of learning at my age. Know that I might be able to eliminate possible issues by disconnecting them to narrow down the possible causes, but not sure where to start. I'll figure it out, and forget it two days later (pre-diagnosed), but if you know of any documentation on the topic, I'd like to have it to review every time I lose my place.
     
  4. Trombone

    Trombone Member

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    You've no doubt already thought of the obvious things, like:
    (1) is your trunk light off when the lid is shut (guess you'd have to crawl in there to find out!)?
    (2)How about the dome light (but this one you could readily see).
    (3)I'm assuming your DRLs go off when the key is out, ditto the headlights.
     
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  5. ronlewis

    ronlewis Active Member

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    I hadn't really had time yet to think much about it yet at all, but just sat down to research. Thanks for some starting points to get me thinking. I've really not driven it enough to know those things yet. This last short trip was the first time it's had doors on it, lol The first two trips, I was kinda distracted and had jumped off the original battery both times, so wasn't surprised when it was dead again both times, even after charging up and getting a green light from my charger both times, dead the next time. But when the brand new one was dead, I knew I had a problem.

    That said, I think the passenger taillight isn't working, which is probably on those same harnesses. Love to figure out if I could eliminate that entire harness as a test. Have to locate the schematics and figure out which one it is. Those are like hieroglyphics to me. Tech like an Egyptian!

    Did just charge up that new battery and started the car, but I haven't driven it. Still did the no-dash-light-until-it-starts thing, but otherwise idled just fine, which he wasn't doing before.
     
  6. ronlewis

    ronlewis Active Member

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    OK, charged the battery and the car runs perfect. And, I got it back from the paint shop and it looks beautiful. Only deal, it's still missing the right fender. I thought the blue parts car had one that was going to work, but those dang auction pics again...it's got a dent and twist that can be fixed, but a PITA. Instead, I thought I'd found a white one at a junkyard, so I'd have to buy it, but not have to paint, so a breakeven vs my free, bent parts car fender.

    But, that yard then called me back and said they don't have it. Then another yard, another white one, same thing. Then a blue one. Each yard said they had it, then changed their minds. ()^&#)%_U% So, now I got a line on a gray one, but the best price - $35! And I'll have to paint it. I'm thinking about rattle canning it. I went cheap with the shop, just paying them to paint the big parts, the replacement doors, hood and two bondo repairs. The car also has some paint blemishes on both bumpers and a wheel well. Since the car is white, and non-metallic (I assume), matching the color should be easy.

    Otherwise, I just have to find the parasitic battery drain and fix that, lol. I hope that goes well. It'll be a nice car with only 72k miles. I'll post pics when I get the fender, I've already detailed the rest of it.
     
  7. ronlewis

    ronlewis Active Member

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    OK, believe me, none of us want to talk about this project. I hate electrical problems. Of all my lamenesses not mentioned in the Bible, electrical problems are the lamest. My children and IRA turned out better than my electrical problems. I already have valuable cars sitting for years because of electrical problems. But, I've never had these electrical problems...

    They're getting worse - while the car just sits there, and worse, while I'm spending all my time and effort making the rest of it beautiful. The rest will be done in a few hours, the car is beautiful. But I've driven/idled it a few times and it has new symptoms each time.

    So, now I'm all invested in this beautiful car that runs perfectly when it runs. $^&&#%@ I gotta fix it. I have no choice. Can't let it sit in the driveway with the others. And y'all definitely want no part of this, except while enjoying popcorn. But, I'll try to document some of it, it my non-nerdy, wordy way that probably won't really help anyone, but let's me reread in my senile confusion. Here's the timeline to now:

    1. jump it at local auction, drive it home, no problem, but didn't look for any. parked it.

    2. jumped it at storage lot to move. nothing lights, dash or displays in ACC, but turn futher to start and car starts, all lights come on, wipers sweep once, and the engine idles Ready then drives with no problem. Move it a few feet.

    3. Drive from storage to paint shop ~2m. Jumps/starts the same way. Drives 1.99m just fine. Dash flickers, dies, restarts briefly, dies, We push it the last few feet to the shop. I buy a new battery, show them how to pull the plug from the + terminal block to, I think, keep any parasitic drain from affecting the battery. They are able to drive in/out of shop.

    4. I drive it home from the shop. No problem, no difference that my senile mind can remember. It sometimes takes more than one attempt, and sometimes the wipers don't sweep, but they try to. but it starts and I finally get it home.

    5. So, I'm finishing my other work on the car. I probably started the car once or twice idling for a minute or two, and one of those times I forgot to unplug the battery overnight. It still started the next day, and I unplugged it. I was hopeful the drain issue was solved, and that I just had the missing dash lights at ACC and strange starting sequence to resolve. I drive it to the auto store for something, drives great for 2m and then dies pulling in their parking lot with the same dead battery symptoms. So, parasitic drain confirmed? Not yet. I used another battery and jumper cables to get it home, OK, and the store tested the battery and it's Bad, unable to charge. So, maybe still the battery, out of box failure, or my car killed it. Replaced under warranty.

    6. So, last night, still using my big 850amp truck battery with cables direct to the car's terminals (haven't installed the replacement battery yet). I'm replacing headlight bulbs/testing those connections. start the car to idle, same strangeness, and after a short idle, it dies and throws the orange triangle/car icon. Key off/on, it won't even try to start again - blank at ACC, and nothing next. Battery still has plenty of juice, connections seem fine.

    Finally, a code, so I break out TorquePro. But it won't connect. I continue to have issues - some of these cars but not others connect, but at best only give me a handful of live data. It's done OK finding upper-level codes. Anyway, it never connects to this car. So I'm forced to disco the battery to see if everything resets. It does somewhat. Car starts same weirdness, displays all light up at Ready, and I let it idle all the way until it warms up and shuts off on its own. All good. Wait a minute, key off, back on, and it doesn't try to start, blank at ACC

    It was late, and I quit there and disconnected the batteries. I expect that it will start again now the the codes/whatever have reset. I need to find out those codes.

    QUESTIONS FOR ANY AUDIENCE:

    1. I know there are pins that can be jumped in the OBDII connector to find various DTCs for the brakes and AC. Are there other terminals that will tell me other DTCs, maybe the ones affecting this car?

    2. And generally, any ideas where to look for electrical issues with those strange symptoms.

    3. The bootleg service manual I have shows some wiring diagrams but I've haven't found large schematics more suitable for a needle-in-the-hay-stack search. If anyone has a link or knows where it is in a service manual, lmk.
     
  8. ronlewis

    ronlewis Active Member

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    LOL, I'm a legend on the Ford diesel forum for things like this - just figured out that my dash lights go out when I turn the headlights on because they were dimmed down all the way on the dash control. But, I'm thinking there's still that issue with the dash not lighting at ACC, and then lighting when the engine starts. I didn't turn the headlights on before or in between those events, so whether the switch was on or off, the dash still changed.

    Not sure about the parasitic drain yet. I've only been connecting my big truck battery to the car with jumper cables when needed. No battery to drain otherwise.

    So, as I thought, when I tried to start it today, it fired right up, albeit with the same dash/wiper thing. It idled perfectly up to operating temp and turned off as it should. Dash/display/accessories all fine once it was Ready. Passenger headlight doesn't work, but the other 3 lights on the harness there do. So, I was trying to swap around bulbs to confirm it's not the harness when I got stuck.

    So, this seems to be the primary issue...

    the car runs and drives fine once it starts and as long as it has a good 12v battery. But now, when I turn it off, it doesn't start again, even with a good battery. The first few times it did that, disco-ing the battery for a few minutes would allow it to start. And it did start today, after sitting all night disco-ed - twice - but now it won't start again. I can't get it to do anything. I've left it disco-ed more than enough time to clear codes, and still nothing. I thought I did that last night too, and it wouldn't re-start then, but it did this morning. So that's where I'm at again today. Just quit for the night, car does nothing.

    My truck battery it's running on still has over 12v. All the fuses in the under-hood box on the driver's side have battery voltage - or not - with key off just like my daily driver Prius that's never had issues. The additional fuses that receive power with key on in Old Reliable, not receive power in the project car. All the fuses in the interior box on the side of the driver's dash don't have 12v in the project car whereas Old Reliable has 12v at all those fuses.

    I don't know what any of that means, that's just as far as I got tinkering around. Still can't make my adapter work to read codes. Not even on Old Reliable which it used to work with. I may have a bad BAFX adapter.
     
  9. ronlewis

    ronlewis Active Member

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    Now, I'm hosed. It still does nothing. Completely dead, no lights, no start, nothing. Connected to a strong 12v battery with cables, no other battery in between. Nothing has been changed from when it would start and run just fine, then when it would start and run fine after clearing codes, and now, when dead. Did I tell you that I whine online as a way to relieve stress?
     
  10. Trombone

    Trombone Member

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    Faulty ignition switch!
     
  11. ronlewis

    ronlewis Active Member

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    That would be good. I found a section in the bootleg manual I have that begins at the battery/ignition switch. It includes that section of the wiring diagram, but the text, the punctuation, is confused. The diagram link is below. Can you/anyone tell me where to check to find my missing power source that could start the engine. Thx.

    "CIRCUIT INSPECTION
    When the ignition switch is turned on, battery positive voltage is applied to IG2 Relay, terminal IGSW of the
    ECM and the EFI main relay (Marking: EFI MAIN) control circuit in the ECM sends a signal to terminal MREL
    of the ECM switching on the EFI main relay.

    This signal causes current to flow to the coil, closing the contacts of the EFI main relay and supplying power
    to terminals +B of the ECM.

    If the ignition switch is turned off, the ECM continues to switch on the EFI main relay for a maximum of 2
    seconds for the initial setting of the IAC valve."
     
  12. ronlewis

    ronlewis Active Member

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    IDK, is there an IG1 relay that needs to perform first? The grammar loses me after "...IG2 Relay," in the text. Does it mean that terminal IGSW also receiving voltage at switch on, or that it's joining with EFI relay (nothing is marked as that on the diagram) in sending a signal to MREL? A keyword search of the PDF manual doesn't show any "IAC valve."

    This isn't going to go well, I don't think, lol.

    ign-wiring hosted at ImgBB — ImgBB
     
  13. ronlewis

    ronlewis Active Member

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    OK, I'm using an Innova Power Probe, but I don't know much about it. I'm using another of my cars to compare data/events to this dead one. I had the Innova connected to one car's battery and thought it would work on the other car without moving the cables. With it connected to the working car, when I tested the dead car's fuses, I got nothing. Moved the cables over to that car and now I do show voltage, but not enough. I'm assuming that is the correct reading.

    With the key off, using Innova connected to my dead car, I get no voltage readings from fuses in the Instrument Panel JB, whereas several in my good car show 12v. I do get 12v on the fuses in the Main underhood JB of the dead car that match up with the good car.

    In my good car, with the key in ACC, I get 3.9V on those IP JB fuses that were getting 12v in the good car. And, if I turn the key to ON, those fuses drop to 2v.

    I’ve also swapped over all the relays in the IP and 3 underhood JBs from the bad to good and good to bad. Everything stayed the same – good car ran find, dead car still dead.

    With the key OFF, the only things I see that work are the trunk light, the dome light in its ON position only, and the blinking immobilizer light. No door locks, no Door mode on the dome light, no Open Door light on in the dash.

    Not knowing anything about electricity, I can imagine the battery is sending 12v as far as the Main JB, which is where the big main fuse, and since I see voltage at the IP JB, even though it’s too low, I’m thinking it means the 12v is making it past that Main Fuse.

    Questions, if anyone knows:

    Where the heck is the “Body Electronic Control Unit? This lousy service manual refers to it many times, and I need to check voltages on its connector, but it never says where it’s at. I have known-good ECUs for all the systems, and it might eliminate some probing to just swap those over one at a time and see what happens.

    Does anyone know if that’s even feasible? Maybe ECUs need to be reprogrammed for another car and don’t just swap right over? IDK.

    Of course, if you know any likely spots between that Main and IP JBs where I could be losing the 12v, please let me know. Or, if that’s not even how it works, maybe there’s not a bad connection between.

    As I read the diagnostic procedures for the individual components that don’t work, like the dash not lighting, the engine not starting, etc., they all start and stop at the various ECUs. The first step, therefore is to confirm the power and communications to those ECUs. Since I can’t find any that do work, I’m guessing it’s a power loss at the network level. But, this service manual doesn’t help much on that. I guess it’s all covered in the Wiring Manual, which I don’t have.

    Crazy, because I know it’s something easy to fix, if I can just find it. It’s probably not a lot of problems, just one. The car ran perfect days ago.
     
  14. ronlewis

    ronlewis Active Member

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    OK, had to get a pic from the dealer. It's apparently behind the IP JB, and assume I have to take the lower dash off to access it. Doesn't sound hard, as long as I stay away from that bezel.

    Still, that's on the opposite side of the car from the wreck. Logically, it seems more likely that something along the passenger side got knocked loose, or pinched and shorted.

    Dang, wish I could get power just to read the codes. Hate flying blind. There's not a lot along the passenger side - door sensors, switches, seat belt, door lock. All that stuff connects to the Body ECU, so maybe I swap in the replacement just to eliminate. But, that's the problem with the way my brain works, thinking like this is a transmission with gears, something mechanical, methodical at a lower level than this electronic stuff. A network ground/short could be anywhere on the car.

    What does that voltage drop mean? Why does the dead car still get 3.9v? And what does it mean when it drops to 2v in the ON position? Law school was simply no help with any of this stuff. As FZ might say, I could make more money as a butcher.
     
  15. Trombone

    Trombone Member

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    Didn't they tell you that in law school? "You can always fall back on that butcher thing if litigating craps out."
    (Just kidding. Don't sue me.)
     
  16. ronlewis

    ronlewis Active Member

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    OK, found a complete wiring diagram for free online. Wow. Here's a pic of the power circuit:

    power-source-diag hosted at ImgBB — ImgBB

    It shows only two connections between the battery and the IP JB, where I'm losing my voltage. And I assume it could also be a bad fuse or problem in the JB itself. As stated above, I have voltage as I should in the Main JB, but none or low voltage in the IP JB. One (well, I would, anyway) would assume that I'm losing my voltage at one of those two connections, or it's coming inso hot it's blowing a fuse in IP JB.

    But, those two connections are fusible links, the 120A on the battery cable and the 100a in the Main JB. The first one can't be blown because I'm getting voltage in the Main JB. And can the second one be blown (I can see the full metal filament through the window) if I'm still getting that 3.9v at the IP JB? I wouldn't think so.

    That kinda leaves the fuses in the IP JB, the IP JB itself, or ???? the Body ECU? Could 12v be coming alll the way to the IP JB, but passing through to the Body ECU first and being degraded down to 3.9v (or completely blocked in Key OFF mode) before making it to the other fuses?
     
  17. ronlewis

    ronlewis Active Member

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    LOL, all the above is wrong. I drilled further into the diagram and found the detailed power circuit. Here's the pic:

    power2 hosted at ImgBB — ImgBB

    #1 is that 100a fuse in the Main JB. You can trace a direct always-on path through the AM2 fuse to the one of the two switches in the ignition switch. But, I don't think that circuit is my problem. I'm thinking it's the other half of the switch. You can see that it has the ACC circuit on it. If you trace that, it feeds the Combination Meter, and then through a closed network to all the ECUs, including the Body ECU that would kill all the lights, accessories, etc. in the car. Like I have.

    That would explain the initial starting sequence - No dash lights and the wipers sweeping once are on that circuit. Then, when I turned the key to Start, that's on the other side of the ignition switch, and it would start. (somewhere in there is overlap, because the wipers sweep when it's starting, not just in the ACC/ON position.

    So, that half of the ignition is a different circuit passing through the AM1 fuse and the IG1 relay. Guess I'll start checking all those in the morning.
     
  18. ronlewis

    ronlewis Active Member

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    And yes, it could be the ignition switch itself, as suggested above. And, as always, it could be none of this because IDK anything about this or reading schematics, lol. Just seems like it should be something to do with the wreck, not the ig switch or wiring on the opposite side of the car. Onward through the fog!
     
  19. ronlewis

    ronlewis Active Member

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    Dang, this car is beating me. So, I go out to confirm all of the above to start my day. With key OFF, under the hood, all the fuses that are supposed to have 12v, have 12v. The IP JB fuses are showing 3.9v, as before. I turn the key to ON to check that, on just to do it, I turned it to START, and dang if it doesn't start. But only runs for 30 seconds stumbling, and throws the red car and orange triangle, Then dies.

    But strangely. So I check the battery and the jumper cables I'm using to connect my big 850 battery aren't getting a good connection - the trunk light is off. It's done that several time, I just reset them to finally get a strong, steady trunk light. But, just dawned on me that I'd had trouble with one of my jumper cable sets before, and realized this one was it. I started the car again, and let it run for 10mins or so. It was still doing the no dash lights/dead at ACC, but then full power, all good, after starting. All the fuses in the JBs were showing 14v.

    I decided to install the new battery I had for it and ditch the truck battery/cables. Did that, strong steady trunk light, and...nothing. Car is back to not starting, all dead. And worse, my fuse voltages are messed up. I'm back to getting nothing from the IP JB at key OFF. Obviously, the codes should have reset while I was switching those batteries. Tried to check them again while it was idling (triangle lit), but still no-go with TorquePro and my BAFX connector.

    What could be making these problems come and go? I thought the Ignition Switch was the most likely problem so went to scavenge that and the ECUs from my parts car. Got all the ECUs and combination meter, but couldn't figure out how to remove the ignition, and haven't found the instructions in the service manual. I see the connectors are easy to access, so I should be able to probe those to confirm voltage - if the car starts acting normal again.

    I did confirm that the inverter coolant pump was turning on with key ON, even when nothing us was working, which I noticed from the schematics should be the case if several of my fuses/connections are good.

    Otherwise, I'm back to square one. Anyone know how to remove the ignition? Is the cylinder all that comes out?
     
  20. Trombone

    Trombone Member

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    You’ve checked the battery-to-ground connection, right? Also the positive battery clamp for good contact? This intermittent problem could be a bad connection, which goes away when you jump with the good set of cables.