Gen 2 Yellowbox calibrator

[GTSGEN2]

Hi
The speedo on my 1999 GTS need to be calibrated due to bigger wheels and different gearing.
I just got my yellow box and tried to install it without succes. I was following the instruction and those are the problems I run into:
1. In the harness leading to the black PCM connector, I was supposed to use the dark blue with gray stripe to feed the yellowbox. There are two blue/gray cables and I don´t know which one to use. In the picture från the instruction, it shows a lighter blue even though it says dark blue. Am I supposed to use the lighter one? One of the blue ones on mine is maybe a little bit lighter, you can barely see the difference.
2. The instruction says that the white wire with orange stripe in the harness leading to the white PCM connector is the speed sensor cable and should be easy to find because it has a separate connection. Mine doesn´t. I found the white/orange wire but it does not have a separate connector, if it isn´t hidden behind tape but I don´t think so. Is this a problem?

Everything else I did exactly as the instruction said but the speedo was dead when I test drove it. The instruction says that the yellowbox is supposed to light up when connected and the power is turned on but my doesn´t.

Where to start the troubble shooting? Picrures are from the instruction.

 

[Gibz]

Ìm installing one Wednesday and I'll let you know how it goes.

 

[Gibz]

Im installing one Wednesday and I'll let you know how it goes.

FYI

I did plan mine out but not cut wires yet- the blue wire with grey stripe should be pin#2 on the black connector, so you can do a continuity test from pin 2 to the blue/grey wire to make sure it is the right one. you can see the pin numbers next to the locations when you look at the face of the connector.

I think the black/blue wire should be pin#4- going off memory here. That is also a ground so you could ring it out to your chassis ground or to pin 4 to make sure.

 

[Dan Cragin]

I can program all year JTEC PCM's for a gear change and supporting mods so you don't need to use the yellow box. PM me if interested.

 

[GTSGEN2]

FYI

I did plan mine out but not cut wires yet- the blue wire with grey stripe should be pin#2 on the black connector, so you can do a continuity test from pin 2 to the blue/grey wire to make sure it is the right one. you can see the pin numbers next to the locations when you look at the face of the connector.

I think the black/blue wire should be pin#4- going off memory here. That is also a ground so you could ring it out to your chassis ground or to pin 4 to make sure.

I used pin 2 and pin 4 without succes. Do you know if pin 28, speed sensor, is correct or should I use nr 27, speedometer signal?

 

[GTSGEN2]

Just tested the black and blue ground pin nr 4 but it isn’t grounded to the chassi. It is ”sensor ground”. Is this OK for ground or should it be a constant grounded wire? Like pin nr 31 and 32 that are grunded to chassi?

 

[Gibz]

pin 4 is a sensor ground and is what you are supposed to use for the Yellow box. Pin 2 the positive. on the white connector, pin 28 is the white/orange vehicle speed sensor that you should cut and intercept for the module to modify the PWM signal coming from the sensor before it goes to the ECU. that then gets relayed to the speedometer in pin 27 with a white/tan wire. dont mess with that.

You can also put the jumper that came with your yellow box onto the YB harness in place of the module. this jumps the blue and white input and output signal wires together to make your car act like the sensor is not there at all. I would try that, it would verify that you have no issues with the signal wire- then it is down to the box or the positive and the ground. then when the car is running i assume you should also be able to measure between positive and ground (red and black in your harness) to see if you have voltage in running state. Are you sure you done have the binary switches so wrong that it is just giving you a very low signal? you can try "no correction" and see if it is ok.


I did not install mine yet, had to finish figuring out how much I owe the IRS first, and I have a friend checking if he can reflash my ECU first maybe I can avoid the headache you have. If/when I do, I'll let you know how it goes.