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D.I.Y. RAD Rock+Rail shifter install with no CEL on a 99

sidewaysstarion

Coffee Drinker
NAXJA Member
Location
Torrance, CA
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Two days so far with no CEL. :repair:
 
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I mounted my RAD shifter in the same location just a little further back. Looks great.

How do the switches and lights work?
You had to cannibalize a 2nd TCU for the plug to make the jumper cable?
 
What strategy did you use to prevent CEL?
 
What I did was wire in 100 ohm resistor between each solenoid output from the TCM and ground. So far this week, no CEL's so far and I've run 1st and 2nd out to the limiter a few times.

I can't tell from the picture what wattage resistors you're using, and the picture doesn't show how they are mounted.

Each resistor will be dissipating 2 watts when the TCU activates the associated solenoid output. Second gear has both shift solenoids on simultaneously, so that's 4 watts. However, the TCU doesn't often want 2nd gear for very long -- that's the whole reason you did this mod! The only time my TCU wants 2nd for more than a few seconds is when I'm towing a trailer up a steep grade and want to go over 50mph.

4 watts isn't much if you have decent air flow or a heat sink, but if the resistors are buried in a wire harness things get mucho toasty!
 
I think I used 330 or 360 ohm resistors. IIRC less heat with them.
 
Sorry, typo, I used 1k ohm / 1 watt resistors. I put on a 14 volt load for close to an hour and they were barely even warm, so instead of 2 watts of heat its .2 watts of heat.

As for the mounting they are spliced into the wires coming out of the TCM in my patch loom and encapsulated in 2 layers to heat shrink and then zip tied to the main bundle of wires.
 
How do the switched and lights work to control the shifter?
 
Figured I'd update this thread, I've been driving it since July with the shifter, drove all over moab and JV and clocked close to 40k miles and still no CEL. I even accidentally tossed the trans into 1st at 80 on the freeway and revved the motor to high hell, but even that didn't set a code.
 
When I tried this method on my 98 I got codes after several days if the TCU asked for second and I asked for third or vise versa. Iirc they were solenoid function codes not electrical fault codes. The difference being that a solenoid function code means the trans isn't in the requested gear, while an electrical fault code is the one where the TCU sees the short or open circuit.

Maybe you just have better luck than me. I may try it again for a while before I drop my ax15 swap in, the last time I tested that method was in 2010 about when raneil did this setup, after that I tested a few modifications to the TCU itself with slightly better (but still not 100%) success.
 
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That's a great setup. I've seen a couple guys try something similar as did I but I haven't heard of anyone before getting 100% positive results. Did you seriously hack up a 2nd harness for this?

Thanks, Yes I did hackup a second harness and TCU to build my patch harness. I have since ordered up the connectors to build more patch harnesses.

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When I tried this method on my 98 I got codes after several days if the TCU asked for second and I asked for third or vise versa. Iirc they were solenoid function codes not electrical fault codes. The difference being that a solenoid function code means the trans isn't in the requested gear, while an electrical fault code is the one where the TCU sees the short or open circuit.

Maybe you just have better luck than me. I may try it again for a while before I drop my ax15 swap in, the last time I tested that method was in 2010 about when raneil did this setup, after that I tested a few modifications to the TCU itself with slightly better (but still not 100%) success.

Do the function codes set a CEL? I know when I would get electrical fault codes the TCU would no longer use that solenoid and pretty much go into limp mode till I reset the TCU. This was the same on my 99 and the giveaway rig, which was also a 99. What is the part number of your 98 TCU? I'd be tempted to find one and test it on my rig.
 
Thanks, Yes I did hackup a second harness and TCU to build my patch harness. I have since ordered up the connectors to build more patch harnesses.

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Do the function codes set a CEL? I know when I would get electrical fault codes the TCU would no longer use that solenoid and pretty much go into limp mode till I reset the TCU. This was the same on my 99 and the giveaway rig, which was also a 99. What is the part number of your 98 TCU? I'd be tempted to find one and test it on my rig.

I believe it's the same as a 99 TCU, but will have to check when I get home. P56041386AA ring a bell? Not entirely sure on that number, so don't put much stock in it.

It definitely set a CEL for me - anytime I was driving like a jackass (occasional heavy throttle, etc) while shifting manually between 2/3 with my tiptronic setup, the TCU would get pissed off if I didn't agree with it.
 
I believe it's the same as a 99 TCU, but will have to check when I get home. P56041386AA ring a bell? Not entirely sure on that number, so don't put much stock in it.

It definitely set a CEL for me - anytime I was driving like a jackass (occasional heavy throttle, etc) while shifting manually between 2/3 with my tiptronic setup, the TCU would get pissed off if I didn't agree with it.

Mine ends in AB, where as yours ends in AA and looking at it your part number seems to be a one year only TCU.
 
Where did you source the DPDT switch for actuating the rail shifter? I found one on DelCity but it has screw terminals.

And when are you coming over to help me wire mine?:eyes:
 
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The real test will be if you keep it mostly in 2 and 3 around town, romp on it a decent amount, switch between the two while doing so. Basically drive it in anger while using 2nd and 3rd and eventually something will happen, it was fine for me till I did that. I found that the TCU wanting to be in 2 and me wanting to be in 3 or vice versa was most likely to cause a CEL.

How are you testing the 98 TCU without having a 4 pulse/rev VR-type OSS installed, or the 97 TCU without having a 1 pulse/rev reed switch OSS installed? Or are you using the converter circuit lawsoncl posted when testing the 97 TCU?
 
My rig a 99 so a 98 TCU is plug and play, I haven't been able to test a 97 TCU yet. I have a 97 TCU, but the connector is different than the 98-01 TCUs. If I wanted to test a 97 TCU I can use a dakota digital box to adjust the PPM of the OSS to make it work.
 
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