I believe that’s next to the passenger kick panel fuse box.
5-speed A750 trans won't shift in to 5th gear. (7 Viewers)
- Thread starter MongooseGA
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2001LC
SILVER Star
Back to basic.
You need to rule out, which in mind you have not. Engine Coolant Temp (ECT).
I bring this up. Since scanning over all your post herein (perhaps I missed it?). You just state ECT as "always appropriate". I like the detail as more than once I've heard here in mud, normal or as should be. When it's not!
Interesting. Now, your AT shops points to a "coolant leak" on AT wire onto of bellhouse, as I understood.
You also mention, a new radiator. Which I find coolant to be low, all to often. After any coolant service or case where coolant dained.
If coolant low in radiator. As seen 8 hours after cool down, before the sun and OAT come up in the AM warming air (expanding coolant). With vehicle level or front end higher than rear (best). We look under radiator cap, into radiator. If coolant low enough, the ECT sensor (water temp), will be in air. Which it does not read air temp. In this case, we get a false low ECT temp.
The wire from ECT sensor to ECM also needs testing for resistance. The ECM is near RH "A" pillar and which is subject to water entry, from bad windshield install.
Make sure the CDL is not engaged. Sometimes the dash light is out or a CDL SW/sensor stuck which signals dash CDL light. But CDL is engaged/stuck. Easy test: Backup with steering turn to a all the in one direction or the other. If ties skipping/binding is felt, CDL on.
You're now focusing on a relay. In the schematic/drawing you posted. It appears to show it to be, near RH junction box. This area and LH junction box/aera, is where water from windshield and or "A" pillar leak cause the most issues. Even and old leak, not currently leaking. May have caused oxidation on contacts, which may increases resistance.
Relay your now looking for. "Any" oxidation or discoloration within a wire housing block or connection. I suspect and must be thoroughly cleaned (shinny)!
You need to rule out, which in mind you have not. Engine Coolant Temp (ECT).
I bring this up. Since scanning over all your post herein (perhaps I missed it?). You just state ECT as "always appropriate". I like the detail as more than once I've heard here in mud, normal or as should be. When it's not!
What is actual ECT temp, while driving and not upshifting to 5th?
Interesting. Now, your AT shops points to a "coolant leak" on AT wire onto of bellhouse, as I understood.
You also mention, a new radiator. Which I find coolant to be low, all to often. After any coolant service or case where coolant dained.
If coolant low in radiator. As seen 8 hours after cool down, before the sun and OAT come up in the AM warming air (expanding coolant). With vehicle level or front end higher than rear (best). We look under radiator cap, into radiator. If coolant low enough, the ECT sensor (water temp), will be in air. Which it does not read air temp. In this case, we get a false low ECT temp.
The wire from ECT sensor to ECM also needs testing for resistance. The ECM is near RH "A" pillar and which is subject to water entry, from bad windshield install.
Make sure the CDL is not engaged. Sometimes the dash light is out or a CDL SW/sensor stuck which signals dash CDL light. But CDL is engaged/stuck. Easy test: Backup with steering turn to a all the in one direction or the other. If ties skipping/binding is felt, CDL on.
You're now focusing on a relay. In the schematic/drawing you posted. It appears to show it to be, near RH junction box. This area and LH junction box/aera, is where water from windshield and or "A" pillar leak cause the most issues. Even and old leak, not currently leaking. May have caused oxidation on contacts, which may increases resistance.
Relay your now looking for. "Any" oxidation or discoloration within a wire housing block or connection. I suspect and must be thoroughly cleaned (shinny)!
- Thread starter
- #83
I was just sifting through posts as I thought I'd include ECT, but looks like it was only trans temp. ECT runs 190-200 all the time, depending on ambient temps and long inclines. Can go up to 205 in extreme situations like driving the crazy inclines in Colorado this summer. Even when my exhaust got hot driving the truck home the first day this issue arose, coolant temps were perfectly in spec. I monitor ECT, trans temp constantly on my SGII. Coolant level is right at the bottom of the neck on the radiator, where the drain hole goes to the overflow. There are a few inches of fluid in the overflow (when cold). Coolant is clean.
The "coolant leak" pointed out by the shop was a weeping heater tee connection. The tees in my truck are the metal ones. I just snugged up all 6 of the worm clamps on them. It is possible these are due for replacement (the rubber) but they're not brittle or cracking at this point. I've had cruisers with bad rubber in this location but these aren't what I'd call "bad" yet. Nevertheless, I'll probably go ahead and order replacements. The shop believes there was just enough of a weep to drip on to the wiring harness connector just at the top of the transmission. They unplugged the connector, noticed some corrosion, cleaned it up and added some dielectric grease.
The first or second night, before taking the truck to the shop, I drove around my neighborhood testing the trans with CDL engaged, in low range, low with CDL, etc. All functions were correct, other than not shifting in to 5th.
I found the relay module today with fresh eyes. Dunno how I missed it yesterday, but it lives directly next to the main ECM. Photo attached. Remove 3 bolts to get ECM out of the way, remove 1 8mm bolt holding the relay module in place, remove 4 other connectors on the same bracket for the ability to remove the bracket, remove old relay and bracket, then do it all in reverse. Took 3 minutes once I laid eyes on it.
I found no signs of water intrusion or corrosion here, but it is quite dusty/ linty. Inside of the old connector looks to be in good shape to my eyes.
Currently I've got the battery disconnected before I try her out this morning. @2001LC , do you know if there should be a "hand shaking" or otherwise a programming of this new (used) module before the truck is happy to read it? I have TS here at the house this weekend, I've also heard there is a method of jumping 2 diagnostic ports and letting the vehicle kind of marinate for 20 minutes before the truck and module are friendly together.
Worth noting (I don't think I did yesterday) that on my way home from the shop, the truck finally threw a readable code! Recall that it has only given me the ABS/VSC/BRAKE lights previously, and they weren't constant. On at cold key cycle and didn't return after being cleared until the next cold key cycle. Yesterday, I got the ABS/VSC/CEL lights. Read it on my Scan Guage as the same p0771 that I read in tech stream earlier this week.
It's also worth noting that there is some "improvement" since putting in the new trans. The truck wants to shift to 5th now. If I alternate between 4th and 5th at 45-50ish mph, there is a very, very slight change in RPM for a moment. Almost like a little hiccup. It also downshifts with the throttle now, where it hadn't before. And when coming to a stop, it slams in to 1st gear like I'm being rear ended by a Smart car. Or worse, a cyclist. I've heard this was a not- uncommon issues in the LS430s, with the fix being a new ECM.
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- Thread starter
- #84
Hell yeah brother I'm classy as s***!
2001LC
SILVER Star
ECT, as it should be.
I use only Toyota Tees and clamps. Once metal tees and screw clamps used, hose are damaged. Hoses will then need replacing, to go back to OEM.
***** I would revisit these wire housing blocks. Corrosion/oxidation/crud inside them, should not have accrued. We can spray with water, and they should not leak water into inside.
This is the best clue to date, IMHO!
Great as it should be, provided Dash light indicted it was locked when on.
IDK, as I've never had to deal with. You'll need to consult the FSM
***** Since this Solenoid test in old AT, than replace AT instatledd and it's tested also. Very unlikely it itself, is the issue. Much more likely the wire leading to it, along it's circuit and some controller of.
2001LC
SILVER Star
I see some rust coloration, which may indicate water entry. Maybe something else or just normal for humidity in your area.
But, has windshield ever been replaced?
But, has windshield ever been replaced?
- Thread starter
- #87
You are correct, there is some rust on top of that bracket arm you circled. I just pulled it open again to check it and that's the only rust in there. The rest of everything is clean. Curious. It looks as though there would have been condensation from the air vent above dripping on to it, but I don't imagine the vent itself condenses
Windshield is not original, but it was installed prior to my ownership 6-7 years ago. If not for that photo, I've never had signs of water intrusion from the windshield before. Common AC drip on the passenger floor mat but nothing else.
I reconnected the battery and took her out for a spin. No change after the module, although I didn't do anything to marry it to the truck other than the battery.
Here's a video going around outside the neighborhood. You can see the shunt coming to a stop when the trans slams in to 1st, and watch the tach when I'm around 45-50mph, shifting the lever from D to 4th.
Dropbox
Paul, am I reading correctly that you'd focus in on the wiring harness and connectors at the top of the transmission? I believe I've located the correct wiring harness p#, I'll see if I can find the receiver that mounts to the trans as well. I assume it will be some kind of bolt on, drop in sensor there?
Note, the dash lights did not come back today in the 5-6 miles I drove it.
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- Thread starter
- #88
I believe this is the external harness I'm looking for.
Looks like there are 3 connections right at the top of the trans behind the engine, and a handful going out to the case and other places. I'm trying to find out of the truck-side of those 3 connections are available.
Ordered the correct harness from my favorite Serra Toyota of Decatur, AL. $148 out the door shipped on a $286 list price. I'll take it!
Looks like there are 3 connections right at the top of the trans behind the engine, and a handful going out to the case and other places. I'm trying to find out of the truck-side of those 3 connections are available.
Ordered the correct harness from my favorite Serra Toyota of Decatur, AL. $148 out the door shipped on a $286 list price. I'll take it!
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2001LC
SILVER Star
Yes! The wire housing block, your AT shop saw coolant on and corrosion inside. We should never find corrosion inside of these wire housing blocks or in any.You are correct, there is some rust on top of that bracket arm you circled. I just pulled it open again to check it and that's the only rust in there. The rest of everything is clean. Curious. It looks as though there would have been condensation from the air vent above dripping on to it, but I don't imagine the vent itself condenses
Windshield is not original, but it was installed prior to my ownership 6-7 years ago. If not for that photo, I've never had signs of water intrusion from the windshield before. Common AC drip on the passenger floor mat but nothing else.
I reconnected the battery and took her out for a spin. No change after the module, although I didn't do anything to marry it to the truck other than the battery.
Here's a video going around outside the neighborhood. You can see the shunt coming to a stop when the trans slams in to 1st, and watch the tach when I'm around 45-50mph, shifting the lever from D to 4th.
Dropbox
www.dropbox.com
Paul, am I reading correctly that you'd focus in on the wiring harness and connectors at the top of the transmission? I believe I've located the correct wiring harness p#, I'll see if I can find the receiver that mounts to the trans as well. I assume it will be some kind of bolt on, drop in sensor there?
Note, the dash lights did not come back today in the 5-6 miles I drove it.
You've also mention some issue with 1st gear IIRC. Looking for common signal point of it and the OD (5th), may prove a useful clue.
The contacts within any housing blocks, both end (male & female). Need to be shiny clean like new. Any corrosion or oxidation which may just look like a slight discoloration. May increase resistance of the wire(s), thus reduce current/signal passing through it.
I'm assume, your replacement transmission did not come with wire harness. If it did, it's not likely it bad (increased resistance) also. But the end that it connects to, may be.
Examples:
Battery post oxidation (gray film), will reduce charging current it receives. Result in battery undercharge, which will then sulfate (will not accept full charge).
Brake control wire corrosion. Increase resistance, resulting in premature commutator failure.
One of my most difficult AHC diagnostic, was found to be corrosion in a wire housing block under the body. This one had multiple issues. I'd fix one and and intermittent one would shut AHC off seemingly randomly. The best clue read ou of +B voltage in tech stream. The +B voltage was changing.
All wire housing blocks under the body, have water tight rubber seal within. Sometimes these seals fail. If they do and get moisture inside. The current traveling in those wires, is affected.
Water down "A" pillars, from windshield leaks. Is not always seen. In fact very often not seen on floor mat, like the AC condensation leak.
These windshield leaks, are from improper install. 100 & 200 series have been totaled by insurance companies. After Dealerships shops, hit a certain dollar amount, trying to diagnose the gremals they produce by water entry.
An AC diagnostic I did, after ~3 dealerships, ~2 AC specialty shops and the mechanic/owner that bought cheap, due to inop AC. Could not get AC working. They replaced almost every part in the AC, trying to get working.
I called out the "cause" within 5 minutes of see the vehicle and talking with owner. Previous windshield water leak, down A pillar!
The current owner had fix (plugged rivet holes in A pillars for side molding) the leak after he bought it. But I suspect, water entry had resulted in oxidation of contacts. Even though water no longer entering cabin. The effects of the water (wetting and drying repeatedly) was was present.
With the help of ih8mud, we found a common point for a few things inop. One being OAT display. It was a common ground fault signal, for RH junction box. This clue, help me to focus my attention to the RH junction box area. I found one fuse in the RH junction box, a bit stuck and oxidation on the prongs. A third clue.
This fuses prongs, should have been clean & silver looking, like new. It was a sure clue of, water entry into RH junction box.
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- Thread starter
- #90
You are correct in the the new trans did not come with a harness, the existing one from my truck was reused.
I'll hopefully get the new one in within a few days and we can go from there.
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The truck side of those connections are part of the main engine wire harness FWIW.
Yeah, but you know where to start looking. SR is the solenoid that's not working the way it should (based both on the code & the symptom of no 5th gear) - I posted how to check the wiring for that back on Page 3. That ought to be pretty straight forward, other than those connectors SUCK to get to with the transmission/engine in place. If you disconnected all 3 main transmission connectors you might have enough slack to pull them up a little bit on top of the rear portion of the engine.
Hah! I'd trade ya electrical diagnoses for a front diff that's *not* grenaded.You shoulda driven 3 hours south on 75 after COTR. I know you love doing long format vehicle diag
When I pulled my entire engine harness, there wasn't actually anything there that ran to the module that you replaced IIRC, just to the ECM. Thats been a minute though, so I could be wrong. The FSM is referring to the connector on top of the transmission though in this case.
If we first look at page DI-310, we see that the solenoid should have a resistance of 11-15 Ohms. I believe you said the tech checked that and it was good.
The next place to check is then at the connector on top of the transmission (page DI-309) - assuming the wiring is good, you should see the same 11-15 Ohms resistance there (since you should just be measuring across the solenoid again).
Then, you plug that connector back in, and measure the wire all the way at the ECU connector. If it's good, you should still see 11-15 Ohms, because again, you should just be measuring across the solenoid. You're checking the entire signal path at this point (outside of the ECU of course)
However, I would actually just measure the resistance at the ECU connector first - IMO, I think that would be easier than getting to the connector on top of the transmission. If you see 11-15 Ohms there, that means you've got good conductivity all the way to the solenoid. If it doesn't measure correctly, that's when I would start trying to get to the transmission connector to try to diagnose where the fault lies - either in the transmission harness, or the main engine harness.
Like @2001LC said, corrosion in these connectors is never good.
- Thread starter
- #98
Probably a dumb question, but would I need the key on for these tests?
Great thinking about measuring at the ECM to start.
Great thinking about measuring at the ECM to start.
No sir, you'll want the key out & the connector unplugged at the ECM.
- Thread starter
- #100
OK lemme get my head straight here. The results at either end are effectively the same thing? Would not measuring at the ECM side be indicative of the solenoid, and measuring at trans connector be indicative of ECM? I'm seeing it as reading what signal is getting through to the other side. Both bad readings would only bad wiring I'd think. Am I off?
