reson46

Thanks to my TPS input voltage issues I was in need of a alternate solution for transmission control. With Trail Jamboree coming up next week I had to figure something out, so I decided to give the TCU the middle finger. I had already wanted to implement some of these changes, and had even wired in a TCU power cut off years ago. Now this gives me full manual control of every gear and the torque converter lockup. I even got fancy with my new estate sale acquisition - a label maker. It will definitely take some practice before I remember every position. After Trail Jamboree I may get even more sophisticated and see if I can figure out a way to control every gear selection with a single switch while the shifter is in OD, but for the short term this will work. Willy

After testing and tracing as many wires as I could figure out how to, making sure every ground was good, and even grabbing a third TCU from the junk yard, I still wasn't able to determine the cause of my low TPS input voltage. With Trail Jamboree coming up next week I had to figure something out, so I decided to give the TCU the middle finger. I had already wanted to implement some of these changes, and had even wired in a TCU power cut off years ago. Now this gives me full manual control of every gear and the torque converter lockup. I even got fancy with my new estate sale acquisition - a label maker. It will definitely take some practice before I remember every position. Willy

Willy, I just looked in my 91 FSM to verify. TCU pin D1 is not used, and D2 is listed as the TPS input pin and goes to TPS pin 3. It's also paralled as a feed to pin 22 of the ECU. So my FSM agrees with the AW4 manual as far as the TPS input circuit. :dunno: Don, I discovered why I was finding so many differences between that AW4 diagnostic document and my FSM wiring diagrams. That diagnostic document is definitively not for Renix MJs/XJs - even though it says 1988 Jeep Cherokee on the title page. That document only includes HO diagnostics. All the diagrams and wire colors are for an HO. I ran through several of the tests as far as I could by matching up corresponding wires from the TCU. I pretty much hit a dead end when a step required me to test an ECU wire. :wall: Willy

Have you heard anything about the status of Barrett Lake? Last I heard it was closed. Willy Its closed most of the year (Its average open time is about 2 months per year!). It opens when the snow melts. Changes every year depending on snow level and accumulation. Here is a good site for info... (expected to open mid-july this year) http://www.hi-landers.com/BLT/BLT.html According to the El Dorado National Forest and other reports I have read it is closed until further notice, along with several other routes. Here is the full list. Barrett Lake is on the second page, route 11N26F. I haven't seen a recent update. Barrett Lake is on our list this summer too. :fs1: Willy

Have you heard anything about the status of Barrett Lake? Last I heard it was closed. Willy

Willy, I just looked in my 91 FSM to verify. TCU pin D1 is not used, and D2 is listed as the TPS input pin and goes to TPS pin 3. It's also paralled as a feed to pin 22 of the ECU. So my FSM agrees with the AW4 manual as far as the TPS input circuit. :dunno: Differences between HO and Renix? I know the throttle bodies are different. Are the TPSs and computers different? Willy

Don, Thanks for the manual. I found another test to try when I get a chance - 7A. I find it interesting that figures 6 and 125 both indicate that pin D1 is not used but my FSM manual shows it as the TPS voltage supply - which I am positive is correct. There is obviously a wire that comes out of D1, and it has voltage. Why does this pretend it doesn't exist? :hmm: Thanks, Willy

D2 is the voltage feed from the TPS to the TCU. D1 is the voltage feed from the TCU to the TPS. The TCU steps down the voltage from 12 volts to 5 volts as the input to the TPS. The power goes from TCU->out TCU D1->TPS->in TCU D2. Whatever is returned to the TCU at D2 is the position of the throttle. I've got the procedure for checking the output voltage of the TPS. The problem is if the input voltage to the TPS from the TCU is off from the start, the output voltage of the TPS will never be correct. Thanks, Willy

How would the solenoids impact the input voltage to the TPS? Do the solenoids provide some type of input to the TCU? I thought they just did what the TCU told them to - shift and lock up the torque converter - without providing any input to the TCU. Thanks, Willy

I am experiencing erratic shifting in my '88 AW4 that I have encountered in the past when the TPS has gone bad. I started my diagnosis by checking the input voltage to the TPS, terminal "D" of the sensor connector. With the key on this should be around 5 volts. Mine was nowhere close. Next I break out the FSM and start looking through the wiring diagrams. It shows the source of the TPS input as pin "D1" from the transmission computer. I check the voltage of this wire coming straight out of the transmission computer wiring harness. It is also very low. Now I start checking the inputs to the transmission computer thinking that it might not be getting enough voltage. I check the voltage to pin "D14", which comes from the battery, and it has 12 volts. I also check the voltage for pin "D16", which comes from the ignition, and it is getting power with the key on. I now know that the computer is getting good input power, but for some reason is not outputting the correct voltage for the TPS. This leads me to think that the computer may be bad. Luckily I have a spare, so I plugged it in. It gives me the exact same results. I could possibly have two transmission computers that are bad, but I tend to think that this is unlikely. Is there a way to test the transmission computer to know definitively if it is bad? If possible I'd like to be able to test both of these computers before I go grab another one out of the junkyard. Is there anything else that could be causing these symptoms? Thanks, Willy

Of course. :doh: Thanks, Willy

What are the side receivers for? Willy

Spent the weekend wheeling the trails around Liberty. After setting up camp Friday evening we checked out what's left of the mining town of Blewett. We found the remnants of the stamp mill. And a short mine shaft. Just before lunch Saturday we had a rig separate the clutch linkage on this climb. We were able to repair it well enough to get him back to camp, then we finished the trail. We hit some snow at the higher elevations. We finished up Sunday with a short trail in the morning. Before we packed up we did a little gold panning and came home with some souvenirs. More pics here. Willy

Finally got around to installing my Christmas present. I wanted a sturdy mount that wasn't just screwed in to a bunch of brittle, 25 year old plastic. I built a bracket that mounts through the center dash vent (not like the AC works anyway :D) and attaches to the metal dash support. Due to the size of the GPS unit it took some thinking to figure out where to mount it without rendering the HVAC controls unusable but high enough to still access the shifter. I ended up mounting it on bearings that allow the entire thing to pivot down and out of the way. I've got a spring loaded plunger on the way that will eventually be installed that will hold it in place when upright and allow it to quickly drop down when needed. Willy

Are you referring to the trails under the power lines or somewhere else? Either way it is not open property, it is owned by somebody, and you are illegally trespassing. The only legal wheeling in that area is at Evan's Creek. Willy

Spent a beautiful weekend on the Olympic Peninsula wheeling Sadie Creek. We had a few casualties - starter, wheel, wheel studs, leaf spring - but everybody made it home safely. The gatekeeper. This used to be somewhat of a challenge, but now it can be driven in two wheel drive. It gets tight in places. The Strait of Juan de Fuca and Canada. Bill's day didn't end so well. Apparently the lug nuts worked there way loose, broke a couple of studs, and wallowed out the lug nut seats in the wheel. Then, after we got back to camp, while we are all standing around talking about how lucky he was it didn't come off on the highway, I noticed that his main leaf was broken. :doh: More pics and a few videos here. Willy

Spent yesterday at Evan's Creek. There is still a lot of snow and ice at the higher elevations. We ran into a group from Venezuela and everybody proceeded to get stuck. We spent the entire afternoon freeing everybody from the snow. On the way back down after the snow started turning to ice. The downhill side did not look like fun if we slid off. This guy had a nice diesel FJ70. Where we spent hours digging, winching, and strapping. More pics here. Willy

Teflon fairleads don't care much for hard pulls at any type of angle. Replaced it with a nice black RE fairlead. Willy

Replaced the Prothane bumpstops with Daystars that are not hard as a rock. Only one trip on them but they seemed to work much better. Willy

Do you have some trained super fabricator monkey laid off from building Ultra4 cars working full time on this thing? I wish I could accomplish things at 1/4 of this pace. :thumbsup: Willy

What's the plan for the uppers? Are you moving the gas tank? Willy

Nice! :thumbsup: Does it have an identity crisis? Does it not know if it is a 4.8L or 5.3L? Willy

Did somebody have a Pepto Bismol fetish? Willy

Looks like you must have had a hell of a drop on the rock slider too. Willy

I see two tail lights in the beginning and only one towards the end...... :hmm: Willy