TheMAN
11-17-2013, 08:42 PM
Not long after I replaced the differential on my van last year, the speedometer started getting sketchy during the course of last summer. Summer 2011 was unusually hot, and after many years of being parked outside, the heat cooked the electronics in the speedometer to death! That wasn't surprising considering that the van is almost 20 years old! At first, the speedometer would read about 10mph off, eventually it got worse and worse till it failed to read higher than 30mph! :o This took the fun out of driving the van and definitely a no go for road trips!
After speaking to my friends who run a garage, they confirmed with me that typically, it's the capacitors on the speedometer circuit board that goes bad. They normally have ones sent out to a specialised speedometer repair shop but their labour isn't exactly cheap! Over the past year, I've been researching and trying to see about just replacing the whole gauge cluster outright with one from Europe since it has a tachometer also. Well, it was a waste of time to say the least. There weren't many to be found, and it was too difficult communicating with the Poles to try to get this to all happen. Then I discovered that, unique to only North America, Toyota changed the harness and connectors in the dashboard since none of these vans here came with tachometers, except for the very rare manual transmission ones the first 3 years the Previa was sold here. :angry: So to even make such a conversion to happen, I would also have to get the connectors with the gauge cluster when buying one from the junk yard somewhere in Europe. Since I don't live there, and I can't really communicate in their language, it wasn't happening. It was either repair mine or buy a replacement from the junk yard, but most of them are in MPH, which doesn't "match" my Canadian spec van... picky aren't I? :wnk:
Then a few months ago, I went to the junk yard with my friend and I happened upon a 91 Previa. I decided it was best to practice removing this **** off of one that wasn't mine and one that no one would care if I broke it. After figuring out how to pull the gauge cluster out, I decided to disassemble the thing only to find that it was fairly simple to pull the circuit board off and replace the capacitors, all without risking breakage of the speedometer! It was decided then that I fix this myself instead of paying someone to do it!
It didn't happen right away though, careful research was needed. I talked to another friend who is an electronics guru and he told me he needed to see the circuit board himself so that he could tell me which specific capacitors I needed. Those cell phone pics were crap he said. :mellow: So I went back to the junk yard and just gave myself a five finger discount on the circuit board. :no: But it didn't end there! A few weeks later, I went to another junk yard and found a 92 Previa, finding out that the circuit board in that one was redesigned and simplified! So I ended up getting that circuit board also, for a nice discount too :wnk:
So two destroyed speedometers later, I figured out all that I needed and the big wait was coordinating between one of my friends who is better at me in removing interior trim plastics, and with my other friend who has steady hands which I put him to use in soldering the new capacitors. :LOL2: So it finally happened these past two weeks!
Skipping to disassembling the gauge cluster...
First you needed to remove three screws holding the bezel/lens assembly onto the housing
https://lh4.googleusercontent.com/-lnvIY6DDg4Y/UESVqAhzHvI/AAAAAAAABHI/mV-7GDJhFes/s1000/gauge front.jpg
You then need to remove the PRNDL display from the bottom side of the housing. After that, you carefully unclip the black plastic bezel from the housing and pull it apart. It is clipped on tight, so some force is needed! Once that was done, all of the screws holding the gauge cluster on could be removed so that you can pull the assembly off the housing. Note: on the 90/91, you may have already removed it as the PRNDL display is electro-mechanical and is connected to the shifter via a cable. Care must be taken on the 90/91 to disconnect the cable before you pull the PRNDL/gauge cluster out! I don't have a 90/91 so I don't know how it's done
https://lh3.googleusercontent.com/-I6V4NQUBF1w/UD3ssLBJFYI/AAAAAAAABGI/FllL64XO-GU/s1000/gaugeback.jpg
A piece of anti-static foam that comes with computer parts packaging comes in very handy. I saved this all these years and it finally came in handy! :D
This is how it looks inside:
https://lh3.googleusercontent.com/-W6G8TlXsTvI/UD3sp4bSOWI/AAAAAAAABFg/KNNVa_kSma0/s1000/gauge inside1.jpg
The circuit board just pulls off with a little force
https://lh5.googleusercontent.com/-XxNeKF5Rjvw/UD3srLLLXOI/AAAAAAAABFw/atiLmP3Gw2E/s1000/gauge inside3.jpg
https://lh5.googleusercontent.com/-eSkjeZTtlug/UD3sqxOwo0I/AAAAAAAABFs/F6-K667ecjE/s1000/gauge inside2.jpg
So I went to meet my friend at his apartment and we "setup shop"
https://lh3.googleusercontent.com/-Hfb0FCNo27E/UD3sriQDFAI/AAAAAAAABF4/k0KnDqN8WbQ/s1000/gauge repair.jpg
Brand new high quality Nichion and Panasonic capacitors were ordered from Digikey.com all for under $7 to my door!
The old capacitors were removed and new ones fitted ready for soldering (circuit board from junk yard on right, shown as reference):
https://lh3.googleusercontent.com/-nVrtkCy8ylI/UD3ssiSvU-I/AAAAAAAABGU/jXwl-XYzy4s/s1000/gauge repair2.jpg
These are the capacitors in question:
https://lh6.googleusercontent.com/-lEy4eL_c9jg/UEf-N4pXngI/AAAAAAAABKQ/zzcC74NttjI/s1000/gauge circuit 92.jpg
I replaced only the electrolytic capacitors, not the two red 10000pF ceramic capacitors since they normally don't go bad.
One of the new capacitors was so much taller than the original, it ran against the odometer assembly! I managed to bend it out of the way, which allowed it to barely fit! :rolleyes:
https://lh4.googleusercontent.com/-wApGs53LOk0/UD3sp-4DD2I/AAAAAAAABFk/trtbW3XVCdc/s1000/gauge circuit2.jpg
Finally, I replaced all the illumination bulbs, and temporarily fitted it back on the van for testing.
On initial start up, the airbag light came on because I ran the engine without the gauge cluster plugged in a few days before. This is normal. The airbag computer checks to see if the light is working properly. If it detects no light, it will set a code! :wall: Also, the speedometer needle jumped up to 60km/h immediately. I gently pulled the needle off and repositioned it to "0". I got out the GPS and got it ready for some ghetto calibration.
https://lh6.googleusercontent.com/-DgBSr_w8ryA/UESdxHlRhPI/AAAAAAAABHY/pPksbzaQWOo/s1000/gauge test.jpg
On it's maiden voyage, the speedometer read too fast. So I ended up pulling the needle off and then driving to 100km/h then engaged the cruise control. While I had someone else watch the road, I put the needled back on at 100km/h the best I could. Afterwards, I was happy to see that the speed was within 1km/h difference from the satnav! Close enough for government work! I tested it up to 125km/h and all seemed well. Below 70km/h, the speedometer would read a little slow, but that's no big deal to me. In fact, the speedometer needle was a little shaky below 50km/h, most probably because these new components aren't original, but I don't really care. The speedometer needle also didn't start moving till I was really going 20km/h. Again, I don't care. For $7, it was a fantastic repair and I would do it again in a heartbeat! I'm pretty sure I saved more than $100!
Oh and before I put this back together, I decided to just get an aftermarket tachometer. It's cheaper and easier than trying to go with the European spec gauge cluster.
See here:
http://www.teoc.ws/community/topic/49982-tachometer-fitted/
After speaking to my friends who run a garage, they confirmed with me that typically, it's the capacitors on the speedometer circuit board that goes bad. They normally have ones sent out to a specialised speedometer repair shop but their labour isn't exactly cheap! Over the past year, I've been researching and trying to see about just replacing the whole gauge cluster outright with one from Europe since it has a tachometer also. Well, it was a waste of time to say the least. There weren't many to be found, and it was too difficult communicating with the Poles to try to get this to all happen. Then I discovered that, unique to only North America, Toyota changed the harness and connectors in the dashboard since none of these vans here came with tachometers, except for the very rare manual transmission ones the first 3 years the Previa was sold here. :angry: So to even make such a conversion to happen, I would also have to get the connectors with the gauge cluster when buying one from the junk yard somewhere in Europe. Since I don't live there, and I can't really communicate in their language, it wasn't happening. It was either repair mine or buy a replacement from the junk yard, but most of them are in MPH, which doesn't "match" my Canadian spec van... picky aren't I? :wnk:
Then a few months ago, I went to the junk yard with my friend and I happened upon a 91 Previa. I decided it was best to practice removing this **** off of one that wasn't mine and one that no one would care if I broke it. After figuring out how to pull the gauge cluster out, I decided to disassemble the thing only to find that it was fairly simple to pull the circuit board off and replace the capacitors, all without risking breakage of the speedometer! It was decided then that I fix this myself instead of paying someone to do it!
It didn't happen right away though, careful research was needed. I talked to another friend who is an electronics guru and he told me he needed to see the circuit board himself so that he could tell me which specific capacitors I needed. Those cell phone pics were crap he said. :mellow: So I went back to the junk yard and just gave myself a five finger discount on the circuit board. :no: But it didn't end there! A few weeks later, I went to another junk yard and found a 92 Previa, finding out that the circuit board in that one was redesigned and simplified! So I ended up getting that circuit board also, for a nice discount too :wnk:
So two destroyed speedometers later, I figured out all that I needed and the big wait was coordinating between one of my friends who is better at me in removing interior trim plastics, and with my other friend who has steady hands which I put him to use in soldering the new capacitors. :LOL2: So it finally happened these past two weeks!
Skipping to disassembling the gauge cluster...
First you needed to remove three screws holding the bezel/lens assembly onto the housing
https://lh4.googleusercontent.com/-lnvIY6DDg4Y/UESVqAhzHvI/AAAAAAAABHI/mV-7GDJhFes/s1000/gauge front.jpg
You then need to remove the PRNDL display from the bottom side of the housing. After that, you carefully unclip the black plastic bezel from the housing and pull it apart. It is clipped on tight, so some force is needed! Once that was done, all of the screws holding the gauge cluster on could be removed so that you can pull the assembly off the housing. Note: on the 90/91, you may have already removed it as the PRNDL display is electro-mechanical and is connected to the shifter via a cable. Care must be taken on the 90/91 to disconnect the cable before you pull the PRNDL/gauge cluster out! I don't have a 90/91 so I don't know how it's done
https://lh3.googleusercontent.com/-I6V4NQUBF1w/UD3ssLBJFYI/AAAAAAAABGI/FllL64XO-GU/s1000/gaugeback.jpg
A piece of anti-static foam that comes with computer parts packaging comes in very handy. I saved this all these years and it finally came in handy! :D
This is how it looks inside:
https://lh3.googleusercontent.com/-W6G8TlXsTvI/UD3sp4bSOWI/AAAAAAAABFg/KNNVa_kSma0/s1000/gauge inside1.jpg
The circuit board just pulls off with a little force
https://lh5.googleusercontent.com/-XxNeKF5Rjvw/UD3srLLLXOI/AAAAAAAABFw/atiLmP3Gw2E/s1000/gauge inside3.jpg
https://lh5.googleusercontent.com/-eSkjeZTtlug/UD3sqxOwo0I/AAAAAAAABFs/F6-K667ecjE/s1000/gauge inside2.jpg
So I went to meet my friend at his apartment and we "setup shop"
https://lh3.googleusercontent.com/-Hfb0FCNo27E/UD3sriQDFAI/AAAAAAAABF4/k0KnDqN8WbQ/s1000/gauge repair.jpg
Brand new high quality Nichion and Panasonic capacitors were ordered from Digikey.com all for under $7 to my door!
The old capacitors were removed and new ones fitted ready for soldering (circuit board from junk yard on right, shown as reference):
https://lh3.googleusercontent.com/-nVrtkCy8ylI/UD3ssiSvU-I/AAAAAAAABGU/jXwl-XYzy4s/s1000/gauge repair2.jpg
These are the capacitors in question:
https://lh6.googleusercontent.com/-lEy4eL_c9jg/UEf-N4pXngI/AAAAAAAABKQ/zzcC74NttjI/s1000/gauge circuit 92.jpg
I replaced only the electrolytic capacitors, not the two red 10000pF ceramic capacitors since they normally don't go bad.
One of the new capacitors was so much taller than the original, it ran against the odometer assembly! I managed to bend it out of the way, which allowed it to barely fit! :rolleyes:
https://lh4.googleusercontent.com/-wApGs53LOk0/UD3sp-4DD2I/AAAAAAAABFk/trtbW3XVCdc/s1000/gauge circuit2.jpg
Finally, I replaced all the illumination bulbs, and temporarily fitted it back on the van for testing.
On initial start up, the airbag light came on because I ran the engine without the gauge cluster plugged in a few days before. This is normal. The airbag computer checks to see if the light is working properly. If it detects no light, it will set a code! :wall: Also, the speedometer needle jumped up to 60km/h immediately. I gently pulled the needle off and repositioned it to "0". I got out the GPS and got it ready for some ghetto calibration.
https://lh6.googleusercontent.com/-DgBSr_w8ryA/UESdxHlRhPI/AAAAAAAABHY/pPksbzaQWOo/s1000/gauge test.jpg
On it's maiden voyage, the speedometer read too fast. So I ended up pulling the needle off and then driving to 100km/h then engaged the cruise control. While I had someone else watch the road, I put the needled back on at 100km/h the best I could. Afterwards, I was happy to see that the speed was within 1km/h difference from the satnav! Close enough for government work! I tested it up to 125km/h and all seemed well. Below 70km/h, the speedometer would read a little slow, but that's no big deal to me. In fact, the speedometer needle was a little shaky below 50km/h, most probably because these new components aren't original, but I don't really care. The speedometer needle also didn't start moving till I was really going 20km/h. Again, I don't care. For $7, it was a fantastic repair and I would do it again in a heartbeat! I'm pretty sure I saved more than $100!
Oh and before I put this back together, I decided to just get an aftermarket tachometer. It's cheaper and easier than trying to go with the European spec gauge cluster.
See here:
http://www.teoc.ws/community/topic/49982-tachometer-fitted/