Resolved 1990 Tachometer fix (no noise filter?)

[dugan33]

Hey, i recently purchased a 1990 talon tsi awd. The tach didnt work so upon looking into fixing it i ran across this well put together thread -> http://http://www.dsmtuners.com/forums/articles-electrical-wiring/414636-how-fix-1990-dsm-tach.html however i dont seem to have a noise filter i know it is a 1990 tsi awd it has a 94 front end swap maybe the ecu is swapped and more? idk why it would be all ive found for evidence is a white wire running along into the firewall. I'll post pics tomorrow..

 

[4g63Powered]

There is a fix outlined in the tech guides (CLICK ME)

If you think there might be components swapped within the car, first thing to do is check your coil pack and transistor. Assuming you have a stock intake manifold, these will be bolted to it on the timing belt side. The wiring for a 90 will look like THIS and THIS.

 

[dugan33]

thank you for the reply. ive been meaning to get to looking at this but ive been busy with the work week. I'm definetely going to take a look at it this weekend and post some pics. the coil pack and transistor look to be stock on a stock manifold, and the harnesses are both there but there looks to be some homeade tape job maybe from a previously attempted tach fix job. i think i just need to find where my noise filter went. its supposed to be bolted on back of manifold i see the spot for it.

attached are some pics of the firewall, harness installed, suspicious white wire, harness that came with the car.

 

[19Eclipse90]

http://www.dsmtuners.com/forums/art...4-ecu-swap-into-1990-dsm-ignition-wiring.html

Check that everything you have matches what this article says as that is precisely what a previous owner has done. When done correctly, the tachometer should work if you are also using the 1991+ ECU. If you want to convert it back and have a 1990 ECU, you have the plugs to do so and can then use the fix linked in post #2.

EDIT: This is not completely correct. Since the coil pack was changed, the signal running to the '90 tachometer will not be correct no matter where the white wire is at. The solution is to either retain the '90 coil pack and the white wire that runs to the noise filter which will then feed the tach or switch to the '91 coil pack, get the tach signal from the '91 PTU, and swap in a '91+ tachometer as well. See the thread linked in post #15.

 

[dugan33]

awesome looks like exactly what im looking for. i'll check it out and let you know how it goes.

 

[dugan33]

i checked it out all the wires were connected accordingly color matched and it had that one spliced like it was supposed to be. i even took the white wire connection from the old solder point and ran a new wire to pin 109 and the tach still didnt work. any more ideas of what to do? could it be my cluster?

 

[steve]

could it be my cluster?

Lets see which cluster you have?

From a wiring perspective you need to make sure you have a connection from the pin on the PTM to the ECU and to the cluster. You'll have to check the FSM for the correct pins of the white wire. I don't have time to look it up this morning.

 

[dugan33]

idk what cluster i have i know its a turbo my talon is a 1990 with a 91-94 ecu swap. thus far ive taken a wire from pin 109 to the white wire off power tansistor and still didnt work. it was already wired from the white wire then extended with new wire to pin 109 off ecu. its the clip furthest to the pass side. i guess i should go about checking the wiring from ecu to the cluster what wires should i follow? i'll tkae a look this weekend.

 

[talon1979]

I have a '90 and got sick of finding and replacing the noise filters that are located on the intake manifold below the coil. I ended up swapping to a '91 plus style and had to alter some wiring as well as change the gauge cluster, coil, & power transistor.

 

[dugan33]

so i know i have a 1991+ ecu, power transistor, and coil packs. i dont know if i have a 91+ cluster. everything works on the cluster except the tach. everything is wired according to the how to: linked by 19eclipse90. I'm thinking il try swapping clusters. i wasnt aware the cluster had to be swapped did you have any tach issues with your swap on your 90?

 

[dacowgod]

so i know i have a 1991+ ecu, power transistor, and coil packs. i dont know if i have a 91+ cluster. everything works on the cluster except the tach. everything is wired according to the how to: linked by 19eclipse90. I'm thinking il try swapping clusters. i wasnt aware the cluster had to be swapped did you have any tach issues with your swap on your 90?

1990 Clusters increment MPH on the 5mph instead of the 0.. so its 5, 15,25,35,45,55 mph etc..

1991-1994 increment starting at the 0 .. so 0-10-20-30-40-50-60 mph and so on..

hope that helps..

 

[dugan33]

1990 Clusters increment MPH on the 5mph instead of the 0.. so its 5, 15,25,35,45,55 mph etc..

1991-1994 increment starting at the 0 .. so 0-10-20-30-40-50-60 mph and so on..

hope that helps..

if that is the case then i have a 1990 cluster. will swapping clusters to a 91-94 fix my issue?

 

[steve]

if that is the case then i have a 1990 cluster. will swapping clusters to a 91-94 fix my issue?

Perhaps. Usually in this case the tach does something but drops out when you rev the engine or bounces around but never reads correctly.

 

[dugan33]

Ya it does nothing at all. im goimg to try swapping clusters tonight anyways. do you know what the output wire is from the ecu to tach?

 

[dugan33]

Im having the same issue but i want to use the stock tach. i swapped clusters, didnt work. i ran new wire from powertransisor to the ecu that is a 91-94 swap. still didnt work. if i run the wire from cas to my ecu will that work or will it wreak my stuff. how about cas to cluster? i need to know what wire behind the cluster is for the tach signal and ground

 

[dugan33]

I know this thread is old . It's so old I forgot I made it when I first got this car. I finally got it figured out. For anyone interested In how I fixed my tach in my car it's well documented here.

http://www.dsmtuners.com/threads/90-dead-tach-with-91-ecu.487334/#post-153487238