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Discussion Starter #1
So... today I fiddled again with my speedo and replaced the speed sensor yet again with a tested good one.

I have two clusters, swapped both and nill.

I pulled out the ecu harness to check for resistance at the speedo pins and that checked good, so there is a good signal to the ecu.

now... somewhere between the ecu and the cluster the signal is lost.

I checked the speed sensor per FSM recomendations and it checked out good. I looked all over to see how to test the cluster to no avail.

Anybody got any idea what to take apart in the cluster or what to do to see the needle move up and down at least?
 

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on the fender wall where the fuse panel is, there are 2 small round connectors in front of the fuse block. I dont know what they're supposed to read, but i know one of those goes to the tach, and one goes to the speedo if mind serves me right.
 

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Discussion Starter #4
@ Lum: I'll take a look into those tonight! crossing my fingers! thanks!

@ Colombo: yeah bro... I was SO disappointed man... I know I can't thank you enough for letting me have it, I just hope it works after all is said and done
 

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Discussion Starter #5
so I looked at the fuse panels, but I don't know what I'm looking for

no round connectors here



and no round connectors anywhere around under the kick panel




can you point me in the right direction please =)
 

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Discussion Starter #6

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That's a helluva find. Hopefully this may be your solution, although a time consuming one. Bookmarked that one.

If you look at this diagram, that Vigman posted a while ago, it appears that the only connection to the ECU is at pin 53. This diagram appears to have the speedo pin numbers for vehicles without air bags.
The other connections at the speedo are---
L (blue) off of speedo pin 16 to speed sensor [pin 14 on the online service manual (OSM) for with air bags]
Y/G off speedo pin 17 to ECU pin 53 [pin 15 OSM with airbags and it feeds to the ASCD not ECU. ASCD looks independent of ECU in OSM]
Y/B off speedo pin 18 to speed sensor [pin 16 OSM with airbags]
B off speedo pin 14 to ground [pin 22 OSM with airbags]
14 and 18 are tied together, so 18 would be the grounded wire on the sensor.
Power to the speedo comes from fuse 10, 2D on the diagram to pin 24 [pin 29 OSM with airbags]

ECU pin 7 goes to the tach (I assume off ECU signal generated from CAS).

I've read in past posts that the ECU may have something to do with conditioning the signal to the speedo. I'm ready to be flamed but I don't see any feedback wire from the ECU to the speedo itself (unless pin 53 is it based on other inputs at the ECU, which wouldn't be a conditioned speed signal back to the speedo), so my theory is that the two wires to the sensor off 16 and 18 would indicate you could test the speedo itself by taking the sensor out to the dash and running some wires off it to 16 and 18, spin the sensor and see if the speedo moves. Don't know if you trust this theory before getting any other comments on it or if you're brave enough to try it. It may prove the speedo works or not.

Which pins at the ECU are you checking for continuity with the speed sensor? That might just blow this theory up.

http://www.zcar.com/dlattach/attach,1455/image/90-96_tech_discussion_forum/sudden_and_profound_blowing_black_smoke_and_5_mpg_893846.0.html

http://www.zcar.com/dlattach/attach,1453/image/90-96_tech_discussion_forum/sudden_and_profound_blowing_black_smoke_and_5_mpg_893846.0.html
 

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Discussion Starter #9
I hear you... although a case of lager should help me through this journey! ;D

although... I'll still just wait for someone else to chime in on testing the signal all the way to back lines of the cluster :p
 

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Yooooo Hoooooooo ( EL-66 )

Sal is the speed sensor in or out of the tranny?? Yellow Black & Blue are the pair with signal!
(A-9) @ tranny.

There is a group of wires behind the passenger side headlight... ( EL-130 )
( A-4/E35 ) 8 pin oval connector.

E-35 ( El-126 ) to E-112 / M-59 ( EL-128 ) ( Pass side under dash, brown rectangular 18 pin connector )

to the gauge cluster ( pin group 11-18 connector ) ( EL-65 )


FISHHHHHHHHHHHHHHHHHH!

Mike
 

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SO... if it was my car I would get an ohm meter ( clip leads etc etc.. )
and buzz out from under the car each wire 1 line at a time eg yellow black from tranny to back of cluster... then the blue

Remember in Japan L= Blue

dumbstone.... ECU 53 Yellow Green F-2/M64 to M-29 ( back of speedo pin 17 ) is the speedo " output " so the ECU can " read " the cars speed.


Here FISHY FISHY!

Mike

Mike
 

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Pin 16 ( at the cluster ) is the RAW pulse train off the tranny speed sensor... pin 17 is ( I assume ) the " buffered " output...

Mike
 

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How to achieve ridiculous post count 101 by Mike "Vigman"
 

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Sal I read the post on TT.net for the cluster solder point breakdown... and it's accurate.. BUT in my humble opinion that is a constant in the universe...

Always a good point to do a touch up on a PCB that is that old, however I'll bet MOST failures are at the actual edge connector from corrosion over time.
AND
Sharing a bit of Mike being a bit to anal...If I have a very intermittant connection... ( works for a few days then crapsout then it works again for no GOOD reason ) sometimes I use a tone generator ( on the feed side ) and headphones on the terminating side to listen to the wiring... eg... I'll pump a 1K signal thru a circuit like this ( multiple connectors ) and wiggle all the connection points and listen for breakup..

Sometimes I'll find a really crispy connection.. as you wiggle it the signal comes & goes.. then I use Caig labs contact cleaner and it's SMOOTH..

Mike
 

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Discussion Starter #17
@ dumbstone: I tested continuity by unplugging the speed sensor and jumping both cables together with a clip. Then tested pin 53 with ground and it did show some resistance, not full continuity tho.

@ Lum: so you are suggesting that these are testing points or just for me to clean and replug?

@ Vig: slow down man! :p hahaha!!! I got waaaaaaaaaaaay lost trying to figure out the diagram itself... I also noted that apparently the speed sensor has a direct connection with the speedo and then to the ecu, or its either that or I have no idea how to read these things XD

 

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Sal......

the line 53 is a FEED ( output ) from the gauge cluster to the ECU

You problem is coming from the speed sensor to the gauge cluster...
Sal does your cruise control work?


Mike
 

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Sal....
The start point is the speed sensor ( generator ) the end point is the gauge cluster....the cluster then " sends " a signal to the ECU.
The Cluster has a circuit ( read buffer ) so you shouldn't get full continuity from Blue to 53

Make sence?

Mike
 

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Discussion Starter #20
ok... so wait... now that I've digested most of your post...

You're saying that at the back of the cluster pin 17 is the direct input from the speed sensor, right?

SO, if I applied some power to that pin I should see the needle move, right?

now if the needle moves, then I know both components are good and working and that the signal just got lost somewhere, eventhough my previous testing proved otherwise...

friggin circuits... if I had the means, I'd convert this sucker back to having a cable like in the good ol' times ¬¬
 
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