Supra Forums banner

1 - 19 of 19 Posts
G

·
Discussion Starter · #1 ·
The wires that came with my defi link gauges were a little too short to make it all the way from the controller to the sensors.
Awhile back, someone told me not to bother cutting and extending the wires b/c it wouldn't work. They said just order the extension harnesses and call it day. Well the harnesses are a complete ripoff for what they are, $32 each or whatever, so I decided to try cutting/extending the wires anyway. It didn't make sense to me how that could possibly not work. Well, it didn't work LOL. Anyone have any idea why?? One harness had two wires in it, and the other had three. I simply cut them and soldered my own wires in between. And for some reason it just does not work! The gauges don't flash red like they are not receiving a signal; they just don't respond at all. It's really weird I think...

-Paul
 

·
488ci V10 Power
Joined
·
1,785 Posts
RSA Supra said:
Just guessing but..... The controller probably knows which gauge signal is what by the resistance/length of the wire or something.
you just think your so smart don't you :p :D








I have no answer to this, so i guess i look like the ass huh :D
 

·
Registered
Joined
·
353 Posts
The Forbidden Supra said:
The wires that came with my defi link gauges were a little too short to make it all the way from the controller to the sensors.
Awhile back, someone told me not to bother cutting and extending the wires b/c it wouldn't work. They said just order the extension harnesses and call it day. Well the harnesses are a complete ripoff for what they are, $32 each or whatever, so I decided to try cutting/extending the wires anyway. It didn't make sense to me how that could possibly not work. Well, it didn't work LOL. Anyone have any idea why?? One harness had two wires in it, and the other had three. I simply cut them and soldered my own wires in between. And for some reason it just does not work! The gauges don't flash red like they are not receiving a signal; they just don't respond at all. It's really weird I think...

-Paul
Paul,

I extended the wire on my EGT gauge and don't have any problems.

-m
 
G

·
Discussion Starter · #5 ·
LOL yeah, I figured I could outsmart those bastards, but I guess not. Actually I'm not certain that my oil temp gauge isn't working; maybe I just didn't let the car warm up enough - It doesn't start reading until 120 F. The oil pressure gauge was definitely not working, however, and I'm positive I soldered everything perfectly. Marcus... your egt gauge extension works? Strange... it must depend on how the sensor works or something.

RSA Supra-
Actually the controller knows which gauge signal is which b/c each sensor has its own set of wires going to a designated spot on the back of the controller. The tricky part is sending the right signal to the right gauge, since each gauge is daisy-chained. I assume they must modulate the signals down the same wire somehow. That isn't my concern, but I thought it was neat how they did that.
 

·
resident smart ass
Joined
·
486 Posts
I have extended my fuel presure gauge over a foot.. no problem once I realized I wasnt pluging it in right. There is no reason why you cant do it that i can think of.. but what really is funny is you said you had a 2 plug going into a 3 or something like htat!! thats not right no matter what you do.. if its a 3 it stays a 3.. so.. check your wireing.. you shouldnt have had to do that.

good luck
 

·
Registered
Joined
·
1,022 Posts
The daisy chained part is probably a I2C serial bus, not an analog line. The result is that the cables must not exceed a certain length. The exact length depends on the hardware, serial protocol, noise, etc. etc.

The analog sensor's wire length shouldn't matter unless its a thermocouple. All EGT sensors I know of are thermocouples, except for AEM's RTD EGT sensor. Thermocouples require a special driver, and that driver needs to know the exact resistance of the wires in between the sensor and itself.
 

·
GOT BOOST?
Joined
·
551 Posts
I got my EGT and Boost gauges extended for over 5 ft. everything works great. I would recomed sodering corectly =). Strip the wires and twist togater then tuch the wires with your sodering iron and let the soder melt through the wires... you need just a little bit to keep the wires togater.

remember that soder is poor condictor and you would build resistance if the wires are not tuching togater.
 
G

·
Discussion Starter · #9 ·
Strawberry Supra-
Huh, no, I didn't plug 3 wires into 2 or anything. I got them hooked up right. I double checked and everything looks fine, good solder etc. I think I'm going to take out my wire and try again with a different wire, and if that doesn't work, try to put the two original pieces of wire back together and see if I can get that working at least. My oil temp gauge is working at least, just not oil pressure.
 

·
resident smart ass
Joined
·
486 Posts
One other really odd sugestion but it was what I was doing wrong.,

When I pulled off the wire I pulled the clip part off the back of the gauge as well. when i put it back on there I put it on backwards so then the wires were not color correct.. ie.. green went to the same spot on the back of the iol presure as it would on the back of the fuel presure gauge. It took me forever cause I couldnt figure out why some gauges would work and the other would not. So I finally pulled off the clip part and turned it around and presto it works fine.

yes I was stupid.. never said I was much of an electrician.
 
G

·
Discussion Starter · #11 ·
LOL nice. I'm pretty sure I got it right, but I will check again anyway. I've been meaning to un-wire what I did and put it back how it was originally to see if it starts working again, then if it does, solder in a different type of wire and try that. Haven't had time. I was wondering if maybe the wire they use is silver and not copper? The resistance of silver is quite a bit less than copper, so putting in even a short piece of copper core wire might have really thrown off the resistance. The wire seemed to solder just fine, which is why I assumed the silverish color was just tin plating or something. I think it's more difficult to solder silver. I'm thinking the defi controller could be calibrated to accept only readings in a valid range of resistances. Originally, I was thinking this wouldn't be possible since defi has their own wire extensions... which would change the resistance... but if they're using silver then that changes everything. Maybe the resistance is 10x off now. Maybe that would explain why those tiny harnesses are so damn expensive too!!
 

·
Registered
Joined
·
570 Posts
i extended mine.. no problems here
 

·
GOT BOOST?
Joined
·
551 Posts
Guys Defi gauges are digital.. They do not have anything to do with resistance. You have 3 wires.. Power, ground, signal. although reistance could be an issue most likely it isnt unless your soder connections are horible.. =)
 
G

·
Discussion Starter · #14 ·
2JZ_MA70-
How do you know the signal isn't a measure of resistance? Just because the gauges/controller are digital doesn't mean the sensors/signals are digital. Many sensors, such as temperature sensors, use a thermal couple which changes resistance according to heat. Pressure sensors I know sometimes use resistance as well, but sometimes they have an IC that converts the resistance into voltage before it sends it down the line.

My solder connections were perfect. I even resolded them with a different piece of the same wire. I turns out the wire was at fault like I had suspected. I just used some very high quality industrial grade silver-core foil-shielded wire from GM and now the gauge works fine! Very strange. I don't know what the problems was, but it must have been related to resistance, either the gauge or material. Or possibly crosstalk between the wires, but I highly doubt it.

-Paul
 

·
Registered
Joined
·
127 Posts
why do all that work?? I Just order extended wires through Defi. Extended wires work fine. I have the whole 7 Gauge Defi system and i have no problems whats so ever. ~ Sam
 
G

·
Discussion Starter · #16 ·
Cuz I'm cheap! LOL. No, mostly I just thought it would be real quick and easy to re-wire them and I didn't want to wait for the harnesses to come in the mail. Anyway, it works now, so I saved myself $60 or whatever. S'all good.
 

·
GOT BOOST?
Joined
·
551 Posts
Paul, The fact that there are only 3 wires going to the gauges and they are linked through eachother, this states that the signal can only be digital. If the signal is variable voltage signal you would need one signal wire per gauge. (other way the signals would interfere with eachother.) The signals from the sensors are procesedby the controler and that signal is converted to a digital signal that caries ID and binary code for every single gauge. The 3 wires are power, ground, signal.....
 

·
GOT BOOST?
Joined
·
551 Posts
The Forbidden Supra said:
2JZ_MA70-
How do you know the signal isn't a measure of resistance? Just because the gauges/controller are digital doesn't mean the sensors/signals are digital. Many sensors, such as temperature sensors, use a thermal couple which changes resistance according to heat. Pressure sensors I know sometimes use resistance as well, but sometimes they have an IC that converts the resistance into voltage before it sends it down the line.

My solder connections were perfect. I even resolded them with a different piece of the same wire. I turns out the wire was at fault like I had suspected. I just used some very high quality industrial grade silver-core foil-shielded wire from GM and now the gauge works fine! Very strange. I don't know what the problems was, but it must have been related to resistance, either the gauge or material. Or possibly crosstalk between the wires, but I highly doubt it.

-Paul
Im sorry did I miss somthing I tought that you are extending the wires between the gauges and the controler???
 
G

·
Discussion Starter · #19 ·
Heh no, I was extending the wires between the sensors and the controller. Sorry if I was unclear.
 
1 - 19 of 19 Posts
Top