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Tach problems, 89 colt w/ 4g63
http://www.4g61t.org/forum/viewtopic.php?f=23&t=22217
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Author:  bfrontin [ Wed Aug 22, 2007 8:42 pm ]
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to4garret wrote:


also, if your running 94 coil packs, how did you convert from the 4 plug to the 3 plug coil pack connector?
I can't remember if it had 3 or 4 wires on the plug but the harness and the coil pack were both from a 94 so no need to convert the plug.
i'd like to kno the answer to this too. Chris, the 91-94 pack u sent me couldnt work cuz there was a triangular 3 pin plug. I can only assume that since it didnt come with a tach adapter on it, maybe that's why they left out the 4th wire as opposed to the 1990 version.

can anyone confirm if and how they got their's to work back?

Author:  to4garret [ Wed Aug 22, 2007 8:43 pm ]
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also, if your running 94 coil packs, how did you convert from the 4 plug to the 3 plug coil pack connector?
I can't remember if it had 3 or 4 wires on the plug but the harness and the coil pack were both from a 94 so no need to convert the plug.
okay then, then it should be a three plug on the coils, which means you probably already used the 94 PTR unit.

ugh, what a mess :lol:

so let me get this right, you've put the tach filter onto the tach signal on the PTR Unit?

i've never heard of it working that way before :S

but anyway, you NEED to tach filter signal going only to the dash, the tach signal from the PTR Unit to the ECU.

that fixes the jumping tach needle.

Author:  to4garret [ Wed Aug 22, 2007 8:44 pm ]
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Quote:
i'd like to kno the answer to this too. Chris, the 91-94 pack u sent me couldnt work cuz there was a triangular 3 pin plug. I can only assume that since it didnt come with a tach adapter on it, maybe that's why they left out the 4th wire as opposed to the 1990 version.

can anyone confirm if and how they got their's to work back?
the 4th wire is the tach filter output wire.

the 3 wire coils dont have them because the power transistor unit supplies the tach signal, not the tach filter.

you can just swap the coils over between the 3 plug and 4 plug and that will work

Author:  89Mirageman [ Wed Aug 22, 2007 8:55 pm ]
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Brian I sent you a 91-94 coil pack, I'm assuming you need a 90 model with the 4 wire plug? My 94 Elantra that I'm currently swapping uses the 90 style dsm electronics and it has the 4 wire coil connection.

to4garret:

Yes, I used the PTU from the 94 engine as well. I read on Lilevo's site that you can use the 90 tach filter on the 91-94 coils to make the tach work. Jason shows you how to wire it up and thats what I did. He says to run the white wire to pin 109 on the ecu wiring I believe, its been a while since I did the swap on my Colt. Anyway if you look at the wiring diagram the white wire on the PTU also runs to pin 109 on the ecu as well. So I tied into that instead of running a new wire for no reason. Pin 109 also ties into the dash wiring for the tach.

Here is the link:

http://www.lilevo.com/turbo/tach/body_tach.html

Author:  to4garret [ Wed Aug 22, 2007 9:10 pm ]
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yup, your right about the tach filter on the coils, by putting the tach filter onto the coils all your really doing to making them 90 coils.

what he is saying in that link is basically what im saying, and also what is in the dsm chips link.

difference between the dsmchips link is, you already have the 94 PTR Unit.

just the difference between the two links, are different ways of going about it.

recap, time...

both links say to get the dash tach to work, you need to output from the tach filter to go to the dash.

the ecu should get the tach signal from the PTR Unit.

now, normally, if you follow Pin 109 where the ecu is, about a few inches above the where it is in the ecu plug (probably under the inspiration tape) pin 109 splits off to the dash and PTR unit. so the wire goes off in a "Y" shape.

find out which side goes to the dash and which goes to the PTR (i used a multimeter) cut the dash one, leaving the PTR going directly to Pin 109.

then run the tach filter output to the wire you just cut off pin 109, that goes to the dash.

done, exactly how i did mine, flawless.

i hope that made some sense lol

Author:  89Mirageman [ Wed Aug 22, 2007 10:44 pm ]
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i hope that made some sense lol
Not really :D but then again I've actually been working on the wiring harness for my Elantra for the past few hours so all the wires look the same right now LOL.

Remember this car was a 1.5 car that I swapped, not an original turbo model. I used Netninja's writeup on the dash wiring found here:

http://forum.4g61t.org/viewtopic.php?t=13766

So you're saying the ecu gets a tach signal from one place and the actual tach in the dash gets its signal from the filter? I have a spare 91-94 turbo harness and when I probe the tach wire on the PTU connector, pin 109 on the ECU connector and the tach wire that goes into the car to the cluster they all seem to be tied in together. What am I missing here? You are saying they shouldn't all be tied together or what?

Author:  to4garret [ Wed Aug 22, 2007 11:33 pm ]
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So you're saying the ecu gets a tach signal from one place and the actual tach in the dash gets its signal from the filter? I have a spare 91-94 turbo harness and when I probe the tach wire on the PTU connector, pin 109 on the ECU connector and the tach wire that goes into the car to the cluster they all seem to be tied in together. What am I missing here? You are saying they shouldn't all be tied together or what?
when they're stock, pin 109 is linked to the PTR and the dash, thats what i was saying about a few inches above where pin 109 goes into the ecu, it splits off in a "Y" shape, one side to the PTR other to the dash.

now the signal from the 94 PTR isnt compatible with the dash. you need to make the dash run off the tacho filter and the PTR needs to go to pin 109 on the ecu.

so they need to be two separate circuits. how you make them separate is up to you.

Author:  89Mirageman [ Wed Aug 22, 2007 11:59 pm ]
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I gotcha now, so if I were to look at a wiring diagram for a 90 dsm it would be separate? Whereas the 91-94's are all tied together. Thanks for the heads up!

Mark, sounds like you have a bit of rewiring to do. Shouldn't be too hard to run the extra wire though and tie it in to the tach.

Author:  to4garret [ Thu Aug 23, 2007 12:03 am ]
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Quote:
I gotcha now, so if I were to look at a wiring diagram for a 90 dsm it would be separate? Whereas the 91-94's are all tied together. Thanks for the heads up!

Mark, sounds like you have a bit of rewiring to do. Shouldn't be too hard to run the extra wire though and tie it in to the tach.
nope the wiring should be the same in the 90 and 94, the difference is in the signal generated but the PTR and Tach filter, as i mentioned early in the thread the PTR's signal is 180 out of phase and probably weaker as well.

the dash wants the signal from the tach filter to work correctly, where as the later model ecu wants the signal from the PTR :)

but when everything is stock i.e. 90, the ecu and dash work happily with just the tach filter.

if you through a 94 ecu into a 90 then it can fudge the signal around some more (my instance) causing the dash to malfunction.

i did heaps of research into this when my tacho was going hay wire.

Author:  stealthtt24 [ Thu Aug 23, 2007 1:25 am ]
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I am so lost right now, what do i have to wire in? haha sorry!

EDIT: i think i understand, i need to take the wire that is running from pin 109 to the dash, make that wire run to the tach filter. then just the pin 109 wire should run to the big plug and VIOLA????

Author:  to4garret [ Thu Aug 23, 2007 1:28 am ]
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I am so lost right now, what do i have to wire in? haha sorry!
read the thread again... slowly... :)

if i get bored i might MSPaint diagram it up later :P

Author:  stealthtt24 [ Thu Aug 23, 2007 1:30 am ]
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Quote:
Quote:
I am so lost right now, what do i have to wire in? haha sorry!
read the thread again... slowly... :)

if i get bored i might MSPaint diagram it up later :P
i put an edit to my post one up, am i right?

Author:  to4garret [ Thu Aug 23, 2007 1:35 am ]
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Quote:
i put an edit to my post one up, am i right?
VIOLA!!! :)

pin 109 on the ECU is white if i recall correctly. and the tach filters tacho wire is also white i believe.

on the tach filter though, if you look at it, it actually has written on it which wire is the tach one.

same with the power transistor unit (PTR "Big Black Plug") it has the tacho wire marked.

so, tacho wire from the PTR -> Pin 109.

tacho wire from tacho filter -> dash.

Author:  stealthtt24 [ Thu Aug 23, 2007 1:37 am ]
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yes the wire on pin 109 is white, but i dont have to mess with the tach wire on PTR to ecu cause its already done, right?

Author:  to4garret [ Thu Aug 23, 2007 1:39 am ]
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yes the wire on pin 109 is white, but i dont have to mess with the tach wire on PTR to ecu cause its already done, right?
well, it should be :)

you just have to follow the pin 109 out of the ecu up the harness a bit till it splits off to the dash, and chop it there.

then connect the tach filter to the wire you just cut off, that gets your tach filter connected to the dash :)

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