Potential Picnic/ipsum Wiring Problem

[Armaitus]

Hello Toyota Owners,

My partner and I have the pleasure of owning an R reg Toyota Picnic automatic. We've owned it for several years now. Sometime last year the vehicle exhibited a strange symptom wherein the dashboard guages appeared to lose input altogether. All of them, fuel level, speed etc. all showed zero. Furthermore the "automatic" would not shift gear. We pulled over at the time and decided to carefully drive the half mile back home and then arrange a trip to the garage to have it checked out. On starting up for the return journey the guages suddenly flared back to life.

This has happened on and off almost 10 times in the 18 months and none of our regular garages can diagnose the cause... in fact it is so sporadic a symptom that it is difficult to reproduce for them. On the last occasion the AA came out only to find nothing wrong.

I am convinced that this may be the cause of loose wiring somewhere behind the dash but have very little experience of these things (my partner is the driver, she has much more knowledge of cars than I do).

I was wondering is any other Picnic owners had encountered similar issues or if anybody had any related wisdom they would be willing to share having read my description of the symptoms?

Any advice would be much appreciated.

Kind Regards,

Armaitus

[miti-babe]

Hi Armaitus

Sounds like you have a sporadic supply problem... There will be a +12V supply line that feeds the instruments and for all guages to fail simultaneously, it's likely that this supply is failing...

The auto-box has it's own ECU to manage the changes, dependant on road speed, throttle position, gear selected, etc... If the G/Box ECU supply is also interrupted, you'll get no gearchanges at all...

So... If there is a common supply for the dashboard and G/Box ECU, your fault lies along that path, methinks..

Better get a wiring diagram...

Miti

[Richard KM]

Hello Toyota Owners,

My partner and I have the pleasure of owning an R reg Toyota Picnic automatic. We've owned it for several years now. Sometime last year the vehicle exhibited a strange symptom wherein the dashboard guages appeared to lose input altogether. All of them, fuel level, speed etc. all showed zero. Furthermore the "automatic" would not shift gear. We pulled over at the time and decided to carefully drive the half mile back home and then arrange a trip to the garage to have it checked out. On starting up for the return journey the guages suddenly flared back to life.

I don't know if you're still having problems, with most Toyotas, the vehicle speed signal goes through the speedo, so if the speedo has a power supply problem, the speed signal doesn't get to the engine/trans ECU. You could possibly have a hairline crack in the circuit board track on the rear of the instrument cluster. You'll probable find that it's copper tracks on a plastic backing.

Otherwise it could be a supply problem to the dash, such as a connection fault at the dash plug, or maybe one of the "Gauge" fuse terminals backing out of the fuse box. Try removing the Gauge fuse and make sure the terminals look like they are in the same depth as the others.

[nz_aj]

I have a similar sounding problem with my 1998 Toyota Caldina, although my temp & fuel gauges still work.

http://toyotaownersclub.com/forums/index.php?showtopic=88166

[Richard KM]

I have a similar sounding problem with my 1998 Toyota Caldina, although my temp & fuel gauges still work.

http://toyotaownersclub.com/forums/index.php?showtopic=88166

Ok, pull the speedo cluster assembly out. You need to remove the LCD odometer display, that's the white plastic box that's mounted into the rear of the cluster with 2 screws and has a circuit board plug that you have to disconnect. Once you have the odometer unit out, take of the black plastic surround off the LCD display, then carefully lever the LCD display from the assembly, keeping it as straight as possible (remember it's glass). Remove the circuit board from the case. There is a chip that has connection problems on the circuit board, in fact, I've found two that have fallen off the circuit board altogether!

I can't remember the markings on the chip, but I think if you have the odometer reset button facing away from you, and the components facing up on the table, the chip is near the edge of the circuit board nearest you. From memory, the markings on the component should then be easy to read, ie, not like you're reading the markings upside down. Either way, if it hasn't fallen off, just resolder it. If it has fallen off, look carefully and you should be able to see from the markings on the 2 soldered connections how it was originally. Reassemble, test drive, and fall over with surprise 8-).

Next time I do one, I'll see if I can remember to get some numbers & pics etc. Hey, there's an idea, maybe I should do my Ipsum 8-).

[edsedseds]

I have a similar sounding problem with my 1998 Toyota Caldina, although my temp & fuel gauges still work.

http://toyotaownersclub.com/forums/index.php?showtopic=88166

Ok, pull the speedo cluster assembly out. You need to remove the LCD odometer display, that's the white plastic box that's mounted into the rear of the cluster with 2 screws and has a circuit board plug that you have to disconnect. Once you have the odometer unit out, take of the black plastic surround off the LCD display, then carefully lever the LCD display from the assembly, keeping it as straight as possible (remember it's glass). Remove the circuit board from the case. There is a chip that has connection problems on the circuit board, in fact, I've found two that have fallen off the circuit board altogether!

I can't remember the markings on the chip, but I think if you have the odometer reset button facing away from you, and the components facing up on the table, the chip is near the edge of the circuit board nearest you. From memory, the markings on the component should then be easy to read, ie, not like you're reading the markings upside down. Either way, if it hasn't fallen off, just resolder it. If it has fallen off, look carefully and you should be able to see from the markings on the 2 soldered connections how it was originally. Reassemble, test drive, and fall over with surprise 8-).

Next time I do one, I'll see if I can remember to get some numbers & pics etc. Hey, there's an idea, maybe I should do my Ipsum 8-).

Hey Richard KM, just would like to say thanks for this hint. The chip had fallen off from my JDM 1997 Caldina GT ST215 4WD Beams. It was rattling around inside the cluster. A bit tricky to solder if you aren't into SMD's, luckily nothing else seemed to melt off. For me the chip had a 76 on it. I made a guess at which way around it goes (there seemed to be a bit of flux residue to give me a clue). It seems to all work fine with the 76 (and other writing) the right way up when looking at the circuit board with the chip at the bottom right. Thanks again, Edd