So frustrated w/this Unitrax speedo box install I am going to lose it!

[PhoenixGTS]

I have done a lot of work to my car, and I have NEVER been as frustrated as I am with this f__king Unitrax speedo correction box install. Here is the story.

Bought a used unitrax speedo correction box (old style with different wires). Installed it per appropriate Unitrax instructions. When installed the car starts and idles fine, but has no timing advance. Sounds like it is effectively firing at TDC. No torque very little power. Disconnect box and car runs fine. Keep box attached and drive for about five miles and it will set a code that indicates fault in #2 ignition coil, but I do not want to drive it that far as is stinks it is so rich (like sulphur from burnt gunpowder) and I think it is risky to the catalytic convertors.

Called Devin (super nice) and checked isntall was ok. Decided used box I bought must be shorted or something and it drawing current from PCM power tap in way to goof up PCM's signal to the ignition coils. Buy brand new latest version of box. Install new box and EXACTLY THE SAME SITUATION !!!

Only thing I can think of now is that this has something to do with me having a Mopar performance PCM and that it is more sensitive to the power tap for the Unitrax box. I will call Devin back on Tuesday after Memorial Day, but any more ideas? Anyone have a Unitrax speedo correction box installed with a Mopar performance PCM?

It there another power source I can use for the Unitrax box so I can stay away from the PCM?

 

[Camfab]

Just get rid of it.

 

[PhoenixGTS]

I FIXED IT! I FIXED! But dang it was MY FAULT all along.

I started thinking this has to be a power tap problem. I went to the service manual with the knowledge that it had pulled the number 2 ignition coil code and sure enough, the wire in the harness for the number 2 coil is dark blue with a tan tracer - which is pretty darn close to the switch power wire I needed which is dark blue with a grey tracer. Dug into the harness and found that someone had tapped the power previously and inserted a purple wire patch. Due to this different color and my sloppy tracing work in the bundle I had tapped into the number 2 ignition coil by mistake. Re-did the wiring and went out for spin.

Car ran great BUT SPEEDO DID NOT WORK! Ugh! Worried that I had fried my new box I stopped and switched the box's interrupt of the speedo signal from pin 27 (as suggested by Devin over the phone) to pin 28 (as in the instructions) and bingo everything is working fine. I assume that since pin 28 is the signal from the PCM to the speedo as opposed to pin 28 being from the speed sensor to the PCM that I now have a corrected seedometer but do not have a corrected odometer. Not sure of that though since the odometer may be getting its signal via pin 28. Who cares it finally works (and of course now that it is hot the battery died during this whole ordeal and I had to replace it this morning since it would no longer take a charge).

So excited to tap up the harnesses real pretty, take a shower, and tap a Corona!

 

[Compensating]

PhoenixGTS...

I have this same unitrax box.. glad to see you found your problem.

The odometer works off the "pulse" sent to the speedo part of the gauge.. it will reflect the correct milage for the "corrected" speed indicated.

only thing... the vipers computer will still track the mileage as indicated by the sensor in the tranny.. meaning the ECU will show higher mileage... but only the dealer can see this.. does not affect much now but might need some explaining when selling or trading..

 

[red98RT10]

congratulations! What a pain in the **** that was!

 

[PhoenixGTS]

only thing... the vipers computer will still track the mileage as indicated by the sensor in the tranny.. meaning the ECU will show higher mileage... but only the dealer can see this.. does not affect much now but might need some explaining when selling or trading..

My PCM mileage is already off due to the switch to the Mopar performance PCM at some time in the car's life.

 

[DEADEYE]

Does someone have illustrated instuctions on the install? I need to remove mine and all I see is a cluster. I tried to do it but the car wouldn't start. I put everything back the way it was. I pretty much figured that I have to remove the box and match the colors on the wires but then I'm left with a red wire and a black wire just hanging there. The red wire has another wire attached (T'd off) and I traced it to the vacinity of the positive battery cable. The black goes there too. Any help?

 

[DEADEYE]

OK, I found this...The guys at Unitrax are SO NICE! For archival purposes here is the answer to my post: The older calibration box is referred to by Unitrax as the RB2120 unit. They tell me the box itself is physically bigger than the newer model.

For 3.55 the 5-6-7 dip switches go to "on" with rest off.

Ground the black, yellow and blue wires to the ground post on the frame right below the PCM.

The center PCM Connector should be White. Remove the cap and find Pin # 27, the White W/Tan wire. You need to cut the white W/Tan wire and connect the Orange wire to the end that still goes to the PCM, connect the white wire to the other end which goes to the speedometer. The left PCM connector should be Black. Remove the cap and find Pin # 2 a Dark Blue W/ White or Gray Stripe wire, DO NOT CUT THIS WIRE just Splice the Red wire to it.

The brown wire of the RB2120 unit is not used (usually wrapped up inside the box so you cannot even see it.

Anyone have any pictures of how they mounted their speedo calibration box? Looks like the toughest part of the install is a clean mount of the box.


Any illustrations?