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wandawoods

Fuel Gauge Fixed - 94 Ls

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Hi Folks,

been super busy in last couple of months, hardly had chances to visit the forum. hoped everyone had a wonderful x’mas and new year.

I finally got a chance to tackle the fuel gauge problem on my 94 LS. before the fix, the fuel gauge needle could only go up to 1/3 max even tank was full. so I followed the instruction found here to replace C142/C147 electrolytic capacitors on the big circuit board inside instrument cluster. I’m happy to report it works like a charm! the fuel gauge is back to normal.

*removing cluster and the 3 darn connectors

of course, you must follow Jim Walker’s infamous procedure:

http://www.lexusownersclub.com/Lexus_Circu...ard_Removal.pdf

I found that the biggest pain in the butt was to disconnect 3 connectors (blue, white & orange) from the back of cluster so that you could take the entire cluster out of the car. on each connector, there is a latch to hold the connector tight in the socket. one will have to manage to press the latch inward and pull the connector out at the same time. it was much easier to say than getting it done because there is very little room behind the cluster and the connectors are pretty darn tight. you need to have lots of patience with very strong fingers too!

*removing old capacitors

when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.

instrument_circuit.jpg

*new capacitors

the soldering work was not difficult to do, one just needs to use very fine soldering tip and keep your hand steady. the C147 is rated 50V/10uf, and C142 is 25V/4.7uf. however, I couldn’t find 25V/4.7uf at Radio Shack, so I used their 35V (max)/4.7uf, and it works!

(note: the ‘V’ really stands for WVDC). pay attention to the orientation of +/- lead from capacitor can. usually, the ‘-‘ lead is aligned with white band on the capacity can.

*my remaining issues:

1. oil level warning light is on despite engine oil is indeed at proper level. does anyone know which capacity is to control this warning light? in fact, does anyone have a circuit layout or wiring diagram for the instrument cluster?

2. the coolant temp gauge remains bad on my cluster. I believe it’s the needle itself, not any bad compoenent on circuit board. when I lift other 3 needles (fuel/rpm/tach) by finger and let go, they will return the lowest position immediately in smooth motion, but temp needle won’t do that, it just stuck, and the center dial is somewhat loose and non-responsive. does anyone know how to change out the needle/dial?

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Super post,CW. TKs for all the effort and congrats on the fix.

All you guys might should 'copy & paste' this and store whereever you file some of this stuff[in case you need in the future and can't find it]

:cheers:

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This is great.

well, I hope my old post helped u.

if u had the circuit boards out, as a preventive measure, u might want to replace the C212 (16v/10uf) on the smaller PCB board. C212 is related to the infamous issue of 'light-out' or 'dark-out' of entire instrument panel when weather is cold on LS400 Gen I (90~94).

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Great pictures :cheers:

My issue with my 94 LS was only the instrument lights not coming on when the car was cold, not until everything warmed up (somes 10-15 mins, sometime 30+). I replaced the Caps with new radial style electrolytic caps... I was actually working on my TV too, when I bought all the caps- had I remembered reading "use titanium as replacement" in the other thread, I would have bought the titaniums. :blushing:

I'll know for sure tomorrow (after a night in the cold) if it solved the problem, but I can tell you that everything fired right up when I tested it. :cheers: :D

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Good job and thanks for the photoshop job! You know I have a tutorial on how to remove the cluster.... http://www.lexls.com/instrumentcluster.html

As a preventive measure you should just recap both boards entirely....I mean...while you're at it, why not do them all?

Just for reference...90-92 clusters are NOT the same as 93-94 clusters ;). For some reason I can't get this through to people! There is no C212 on our 90-92 boards! Saying this fixes 90-94 clusters is just not true :whistles: . I used to think 90-94 clusters were the same but then I looked into it more and saw they were not.

I'm glad to hear you've got a working cluster now wandawoods :)

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Ok i think i am more confused as to what capasitor(S) to get from Radio Shack to fix this cluster issue. Keep in mind my car when it is cold outside the clusters don't light up until 15+ mins later on or when the car is fully warmed up.

Thanks.

uche@wam.umd.edu

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Ok i think i am more confused as to what capasitor(S) to get from Radio Shack to fix this cluster issue. Keep in mind my car when it is cold outside the clusters don't light up until 15+ mins later on or when the car is fully warmed up.

Thanks.

uche@wam.umd.edu

look at this picture of circuit board (93-94 LS400):

instrument_circuit.jpg

C212 (16v/10uf) will be the one needed to be replaced. however, if you have 90~92 LS400, then there is no C212 on board according to lexls.....

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Ok i think i am more confused as to what capasitor(S) to get from Radio Shack to fix this cluster issue. Keep in mind my car when it is cold outside the clusters don't light up until 15+ mins later on or when the car is fully warmed up.

Thanks.

uche@wam.umd.edu

look at this picture of circuit board (93-94 LS400):

instrument_circuit.jpg

C212 (16v/10uf) will be the one needed to be replaced. however, if you have 90~92 LS400, then there is no C212 on board according to lexls.....

so for example the one that says c212 i will go to radio shack and get 16v/10uf capacitor to replace it with?

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Great pictures  :cheers:

My issue with my 94 LS was only the instrument lights not coming on when the car was cold, not until everything warmed up (somes 10-15 mins, sometime 30+).  I replaced the Caps with new radial style electrolytic caps... I was actually working on my TV too, when I bought all the caps- had I remembered reading "use titanium as replacement" in the other thread, I would have bought the titaniums.  :blushing:

I'll know for sure tomorrow (after a night in the cold) if it solved the problem, but I can tell you that everything fired right up when I tested it.  :cheers:  :D

You mean "Tantalum Caps" ... yes, they are definitely the way to go. Besides replacing the caps, there is also a transistor (TR109) that causes the panel lights to go out / flicker / come back in when warmed up. See the "pinned" post on "replacing burnt out needles on intrument panel" on the forum page.

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I was wondering if anyone could tell me if this would work for me...i have a 91 ls400 and the gas gauge just kinda went from a quarter tank to nothing the other day and wont move, also the low fuel light hasnt come on yet so im waiting for it to get low enough to see if that will turn on. thanx

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I was wondering if anyone could tell me if this would work for me...i have a 91 ls400 and the gas gauge just kinda went from a quarter tank to nothing the other day and wont move, also the low fuel light hasnt come on yet so im waiting for it to get low enough to see if that will turn on. thanx

when my caps and transistor on the instrument panel went out, the gas gage took for ever to come up some - never made it to full. The empty light would still come on but atleast a gallon too late leaving little room to reach a gas station. (now that I have fixed my gage and know at what level it comes on) I kept track of when I need gas by using the trip gage - set to zero when full - fill after 300 miles.

quite likely, you need to fix the caps mentioned in this thread to get back your fuel gage. The E light should come on.

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He has a 91, it's a different cluster than yours...read my last post above. Different years, different clusters, different caps. Why is this so hard to understand? In the 90-92 I have found at least one cap that's way out of spec...tutorial coming.

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Hi Folks,

been super busy in last couple of months, hardly had chances to visit the forum. hoped everyone had a wonderful x’mas and new year.

I finally got a chance to tackle the fuel gauge problem on my 94 LS. before the fix, the fuel gauge needle could only go up to 1/3 max even tank was full. so I followed the instruction found here to replace C142/C147 electrolytic capacitors on the big circuit board inside instrument cluster. I’m happy to report it works like a charm! the fuel gauge is back to normal.

*removing cluster and the 3 darn connectors

of course, you must follow Jim Walker’s infamous procedure:

http://www.lexusownersclub.com/Lexus_Circu...ard_Removal.pdf

I found that the biggest pain in the butt was to disconnect 3 connectors (blue, white & orange) from the back of cluster so that you could take the entire cluster out of the car. on each connector, there is a latch to hold the connector tight in the socket. one will have to manage to press the latch inward and pull the connector out at the same time. it was much easier to say than getting it done because there is very little room behind the cluster and the connectors are pretty darn tight. you need to have lots of patience with very strong fingers too!

*removing old capacitors

when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.

instrument_circuit.jpg

*new capacitors

the soldering work was not difficult to do, one just needs to use very fine soldering tip and keep your hand steady. the C147 is rated 50V/10uf, and C142 is 25V/4.7uf. however, I couldn’t find 25V/4.7uf at Radio Shack, so I used their 35V (max)/4.7uf, and it works!

(note: the ‘V’ really stands for WVDC). pay attention to the orientation of +/- lead from capacitor can. usually, the ‘-‘ lead is aligned with white band on the capacity can.

*my remaining issues:

1. oil level warning light is on despite engine oil is indeed at proper level. does anyone know which capacity is to control this warning light?  in fact, does anyone have a circuit layout or wiring diagram for the instrument cluster?

2. the coolant temp gauge remains bad on my cluster. I believe it’s the needle itself, not any bad compoenent on circuit board. when I lift other 3 needles (fuel/rpm/tach) by finger and let go, they will return the lowest position immediately in smooth motion, but temp needle won’t do that, it just stuck, and the center dial is somewhat loose and non-responsive. does anyone know how to change out the needle/dial?

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Thanks for the excellent info on the fuel gauge fix. Worked like a champ on my 93 LS400. Any info on fixing poorly illuminated needles. My rpm needle only lights up about 3/4. Any help would be greatly appreciated. Thanks

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Hi Folks,

been super busy in last couple of months, hardly had chances to visit the forum. hoped everyone had a wonderful x’mas and new year.

I finally got a chance to tackle the fuel gauge problem on my 94 LS. before the fix, the fuel gauge needle could only go up to 1/3 max even tank was full. so I followed the instruction found here to replace C142/C147 electrolytic capacitors on the big circuit board inside instrument cluster. I’m happy to report it works like a charm! the fuel gauge is back to normal.

*removing cluster and the 3 darn connectors

of course, you must follow Jim Walker’s infamous procedure:

http://www.lexusownersclub.com/Lexus_Circu...ard_Removal.pdf

I found that the biggest pain in the butt was to disconnect 3 connectors (blue, white & orange) from the back of cluster so that you could take the entire cluster out of the car. on each connector, there is a latch to hold the connector tight in the socket. one will have to manage to press the latch inward and pull the connector out at the same time. it was much easier to say than getting it done because there is very little room behind the cluster and the connectors are pretty darn tight. you need to have lots of patience with very strong fingers too!

*removing old capacitors

when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.

instrument_circuit.jpg

*new capacitors

the soldering work was not difficult to do, one just needs to use very fine soldering tip and keep your hand steady. the C147 is rated 50V/10uf, and C142 is 25V/4.7uf. however, I couldn’t find 25V/4.7uf at Radio Shack, so I used their 35V (max)/4.7uf, and it works!

(note: the ‘V’ really stands for WVDC). pay attention to the orientation of +/- lead from capacitor can. usually, the ‘-‘ lead is aligned with white band on the capacity can.

*my remaining issues:

1. oil level warning light is on despite engine oil is indeed at proper level. does anyone know which capacity is to control this warning light? in fact, does anyone have a circuit layout or wiring diagram for the instrument cluster?

2. the coolant temp gauge remains bad on my cluster. I believe it’s the needle itself, not any bad compoenent on circuit board. when I lift other 3 needles (fuel/rpm/tach) by finger and let go, they will return the lowest position immediately in smooth motion, but temp needle won’t do that, it just stuck, and the center dial is somewhat loose and non-responsive. does anyone know how to change out the needle/dial?

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Hi Folks,

been super busy in last couple of months, hardly had chances to visit the forum. hoped everyone had a wonderful x’mas and new year.

I finally got a chance to tackle the fuel gauge problem on my 94 LS. before the fix, the fuel gauge needle could only go up to 1/3 max even tank was full. so I followed the instruction found here to replace C142/C147 electrolytic capacitors on the big circuit board inside instrument cluster. I’m happy to report it works like a charm! the fuel gauge is back to normal.

*removing cluster and the 3 darn connectors

of course, you must follow Jim Walker’s infamous procedure:

http://www.lexusownersclub.com/Lexus_Circu...ard_Removal.pdf

I found that the biggest pain in the butt was to disconnect 3 connectors (blue, white & orange) from the back of cluster so that you could take the entire cluster out of the car. on each connector, there is a latch to hold the connector tight in the socket. one will have to manage to press the latch inward and pull the connector out at the same time. it was much easier to say than getting it done because there is very little room behind the cluster and the connectors are pretty darn tight. you need to have lots of patience with very strong fingers too!

*removing old capacitors

when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.

instrument_circuit.jpg

*new capacitors

the soldering work was not difficult to do, one just needs to use very fine soldering tip and keep your hand steady. the C147 is rated 50V/10uf, and C142 is 25V/4.7uf. however, I couldn’t find 25V/4.7uf at Radio Shack, so I used their 35V (max)/4.7uf, and it works!

(note: the ‘V’ really stands for WVDC). pay attention to the orientation of +/- lead from capacitor can. usually, the ‘-‘ lead is aligned with white band on the capacity can.

*my remaining issues:

1. oil level warning light is on despite engine oil is indeed at proper level. does anyone know which capacity is to control this warning light? in fact, does anyone have a circuit layout or wiring diagram for the instrument cluster?

2. the coolant temp gauge remains bad on my cluster. I believe it’s the needle itself, not any bad compoenent on circuit board. when I lift other 3 needles (fuel/rpm/tach) by finger and let go, they will return the lowest position immediately in smooth motion, but temp needle won’t do that, it just stuck, and the center dial is somewhat loose and non-responsive. does anyone know how to change out the needle/dial?

:(

I replaced C142, C147 & C212 and my fuel gage is still not working! When turn on the ignition, needle move up only 1/4 of an inch, fuel light lit up, and I know I have a full tank of gas!

Any other suggestions? Please Help!!

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I finally got around to fixing the instrument cluster on my '94. When I bought the LS400 a few years ago, only the fuel gauge was exhibiting any symptoms. Toward the end of this past winter, started having the cluster lighting out until the car warmed up for a while.

Over the summer, the problem worsened considerably, with the sticking tach and speedo presenting a couple months back. And now with just cool nights, the dark cluster syndrome has returned.

Well, I was pleasantly surprised how quickly the repair went. While releasing the connectors from the back of the cluster was a bit tedious, it was not technically difficult. The cluster was out in less than 20 minutes, C142, C147 and C212 were replaced, and the unit re-installed in just 1 1/2 hours. Not a hitch.

For the first time since I bought the car, the fuel gauge works. And so far no dark dash. Woo-hoo!

Thanks to Wanda Woods, Jim Walker and lexls.com for the great instructions and pix.

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