A8 is a single pin. You have to connect the wire, run the wire thru the unpopulated hole on the connector, and plug the connector back in.

 

Ah, I see. I must admit that I have never done such work before. I had gotten me a set of various clamps and connectors hoping they would fit along with some electric cable I had left over, but it won't work this way, they don't fit through the connector plug, they are too thick. The only stuff I could find around here at a quick glance is some very thin florist wire and a wheel spoke from a bicycle. I could just stick the spoke through the connector and then run some wire from it to the body for ground. It has no isolation though and it can slide out, but I think it shouldn't matter as I am only using it while the car stands and I don't think there is much voltage or amperage going through. What do you think?

 

Now that I have found the TCM in the trunk I am wondering what it is that I have found attached to the TCM mount. I has a 3 port electric connector and that stub on the back side almost looks like a vacuum port, but there is not vacuum line around here. It has a GM logo and a no. on it: 4892294.

That red paint is from welding the rear windshild frame. Just wondering if it could have harmed the TCM or anything else related to my issue.

 

80s vintage Chevy/GM MAP sensor


Cheers
DD

 

Get some fine stranded insulated wire, like 22 or 24 gauge, strip of a small amount of insulation, and wrap it tightly around the pin. Feed it thru the connector block. Make sure it doesn't short to any other pin.
​​​I tried finding replacement pins for those connectors with no luck. I managed to modify another female connector pin I had to fit over A8 that would still allow me to fit the connector back on the TCM. If you have a fine tip soldering iron you could also solder a wire onto that pin.

 

I tried various wires that I had at hand, but none of them worked, no TWL flashing. Either I had a bad connection to the pin or they where bad conductors (or the trunk floor is not grounded what I doubt). I don't know a shop around here where I could get better equipment, maybe in the internet only. Or I could ask a car shop, maybe they can support me.

At least I finally managed to get the cap off the diagnosis port, took me a vice grip and WD40.

 

Ok, ignition on, but engine off, briefly short the pin to ground, count flashes. Nothing happens?
Does the transmission fault light come on briefly when you start the car? It should, then go out.

Jon

 

That's what I did. The TWL comes on just like you describe, so in general I think it's working as it's supposed to be.

 

Well, now that I have sorted out the suspension issues, I can further concentrate on the transmission issue, which is the only major issue remaining on the car.

I gave up on getting the fault codes read, because I think there is only one error code that will set under the observed circumstances. So I think it's not worth paying a few hundred bucks for having it diagnosed or getting myself a JDS/FDS2000 in working order.

For about 300$ I could get a refurbished valve body (though not quite sure whether this one will fit my transmisson). Alternatively I could get the parts and overhaul mine myself, but that would be about the same cost but more labour ... and risk of messing something up.

Adding a new internal wiring harness, pressure regulator, speed sensors and maybe new checkballs, I should be able to adress most of the commonly known issues with the GM 4L80E for about 500€. A complete overhaul at a shop would cost me at least 2500€ + costs for removal and re-installation, so maybe a total of 3500€.

If that doesn't fix my issue, it is verly likely the converter itself ... or maybe the oil pump, both transmission out-jobs. Then it would be time to think about a complete overhaul.

I observed that many shops are thinning out their 4L80E-assortment, so I think it is no use waiting much longer or I might be running out of parts.

I think I could do all the valve body removal and installation myself, so this would cost me nothing but some time and elbow grease. The biggest issue I see here are indeed the exhaust pipes which restrict access to the oil pan. Since I do not want to crack my newly installed exhaust manifold I would maybe go the easy way and just cut them off if they don't want to come off without a fight. For reinstallation I would simply clamp some sheet metal wraps around the cuts and seal them with exhaust gum.

What do you think?

Oliver

 

Be aware that the Jaguar version of the 4L80E uses a different internal wiring harness, and a different pan gasket than a "normal" 4L80E. They are specific to Jaguar and Rolls-Royce. Why, I have no idea. New wiring harnesses are not available from Jaguar, but I found a guy on ebay in Canada who repros them. The pan gasket can be had from Jaguar specialists. Here's a link to the Canadian harness supplier.
https://www.ebay.com/itm/11370752560...mis&media=COPY
There are three or four internal solenoids. I used genuine GM parts to replace mine.

Jon

 

Thanks, that's a valuable information, I wasn't aware that even the internal wiring harnesses were different from standard GM parts!

I am still not quite sure whether a MY 93 would have the temperature sensor separate in the valve body or integrated to the harness. When I look at my MY 93 workshop manual it is described as a part of the valve body. In the MY 96 Transmission manual provided in this thread it is described as part of the harness and so is the description of the harness you just linked. Should there be even two versions of the Jaguar harness? And would it really matter as long as they connect to the same pin on the TCM? I'd like to have all parts available here before taking things apart, as it might take weeks to have them shipped from overseas.

There are so many parts out there, it is difficult to keep an overview. There seem to be no-name solenoids (e.g. https://www.ebay.de/itm/194076718104....c101506.m1851) available and I also found AC Delco which I think was the original supplier. Pricewise that is a different story and will mess up my calculation. Then there is a company called Sonnax which claims to provide some improvements over the original parts, but some require drilling holes ... similar to this: https://www.ebay.de/itm/255511400159...XBJ9NZ96CXF6F5.

Actually I want this operation to have as little impact as possible and not harm any working part. This (https://www.lbmautoparts.com/de-de/a...perior/S34165E) seems to be an original regulator kit. This swedish supplier seems to have almost all the parts, but he is more expensive.

By the way, I observed another questionable behaviour: When I start moving from standstill sometimes it first accelerates normally but after a few meters there is a little interruption of force closure and then it returns to accelerate normally again. Last week I had to stop just after I had left my driveway due to opposing traffic, so I was standing still being in second. The street here has a little rise, so when I stepped off the brake pedal and onto the throttle after traffic had passed, the car just began to roll backwards, the engine revved, but no force closure. After my first confusion had passed, I shifted into neutral and then back again into drive and it started off normally again. I hope this just a fluid level issue, will check that again.

 

AC Delco is the OEM supplier.
There is only one internal wiring harness part number for the Jaguar 4L80E tranny. The temp sensor is integrated into the harness, and there isn't a separate part number for it from Jaguar, although it does have a connector on it.The external harness connector is different than other 4L80E harnesses and location of the exit from the tranny body is different. The normal connector is plastic, and the Jaguar connector almost looks Mil-spec metal.
I'd replace the manifold pressure switch assembly, the 1-2 shift solenoid, the 2-3 shift solenoid, the PWM solenoid, and the variable force motor. All are replaceable without dropping the valve body. All are standard GM parts.
If there isn't a whole lot of crud in the pan or filter, and the fluid isn't badly burned, i wouldn't mess with changing the whole valve body.
I went thru this learning process myself, and ordered a stock harness and pan gasket, delaying my service. Hopefully, this will save you some grief.

Jon

 

So with this kit + wiring harness (+ oilpan service kit) I should be complete? The parts catalog lists two different force motors, I guess depending on the tranny no. But suppliers only list one version from 1990 to the early 2000s.

The naming of the parts seems to be slightly different but after some research I believe that force motor and EPC solenoid are the same, as well as TCC solenoid and PWM. Not having to drop the valve body would make things even easier.

What were the issues that you had with your tranny? On mine there clearly seems to be an issue with the TCC. When I accelerate with a certain amount of throttle above 80kph, a situation where the TCC should disengage, I usually get the TWL, at least when the transmission is on temperature. Last year I even noticed a slight disruption of force closure when the issue occured, but this year I mostly do not notice it. Not sure if that means that the TCC doesn't engage any more at all.

When I coast down to about 60kph, I observe TCC shudder basically by seeing the rev counter flinching up and down a couple of times, at least when the TWL is already on.

According to my studies, TCC issues can be caused either by bad wiring, bad TCC solenoid, bad oil pressure or bad TCC. This action would adress 3 out of these 4 causes. There is a little chance that the issue is within the TCM to tranny harness, but I believe that is rather unlikely as all other functions seem to work as supposed. And since I can feel something happening with the TCC, a signal basically seems to be there but just doesn't get implemented correctly.

The error code somehow indicates that it could also be related to either engine speed (this signal should be coming from the ECM, shouldn't it?) or input speed sensor. But I do not quite understand how this would make any sense since the tranny is, as far as I can tell, at least trying to do the right things at the right speed. If one of the speed signals would contraindicate TCC operation, the TCM should not even attempt to engage or disengage it, should it?. Anyway, as these sensors are known to fail, I will replace them, just to minimize error causes.

But there is one thing I am wondering about: looking at the transmission manual and the connector pins of the TCM, there is, as far as I understand, no pin directly related to TCC. So how does the TCM control TCC application? And even if there was a pin/direct wire how does it know whether engagement/disengagement of TCC was successful or not? Are these connections bidirectional? Will the TCC solenoid acknowledge successful TCC operation by sending a signal to the TCM? Or will this somehow be derived/calculated by the TCM from other parameters/signals (e.g. increment or drop of input or output speed through TC)?

 

That kit looks OK, assuming the AC Delco parts are genuine. I didn't replace the speed sensors. You'll need a new filter, filter seal, and the pan gasket, as well as Dextron tranny fluid. The filter and filter seal are standard GM parts. The filter seal may come with the filter, but I don't recall.
When I first got my car, it would go into limp mode and throw the warning light, and it did it pretty often. Blink codes (this was before I got my PDU) said it was one of the solenoids, don't remember for sure which one, but I'm pretty sure it was one of the shift solenoid B codes. I replaced the lot while I was in there. I still, very rarely, get the warning light when the car is cold and I just start moving at the first shift, but a quick restart clears it. It doesn't happen frequently enough for me to worry about it.

 

I just started to calculate ... wiring harness, AC Delco kit, service kit, ATF, shipping + taxes + customs will quickly add up to round about 700€.

Time to think this over ... if it will fix my issues I am ok with that but for a shot in the dark it's a bit too much. I already spent 2k€ this year for suspension + tyres + various other things. Gotta start to think economically, this is not my daily, it's just a fun car that I drive about 2-3k miles per year.

Are the aftermarked solenoids so bad quality that it's no use trying them? Aftermarket stuff would save me about 150€ here. Since I do not have shift problems (except 1-2 shift which I think is a bit harsh under load from the factory) I think it is even not necessary to replace the A+B shift solenoids.

Considering the luck I had with this car so far, it will be very likely the most expensive cause in the end.

Maybe I should first try to measure the wiring between TCM and TCC solenoid as well as the speed signal wires. Just need to know the right pins ... and get some better measuring equipment. Once I can exclude the external harness as cause, I can dig into the valve body.

 

I have been there.

• For your TCC issue, I would definitely measure the TCC solenoid resistance (and wiring). If the TCC solenoid is broken, just change that.
• I would also recommend to measure the line pressure and see what happens when the TCC is about to engage or drops out.

Working on the valve body is not for the faint of heart:

• You will need to drop one side exhaust pipe at least to be able to remove the trans fluid pan. If your center exhaust pipes are as rusty as mine, you won't get them out of the center silencer, which will make you a very unhappy person. Unless you cut your pipes and put them back together somehow.
• When you take the valve body off, make sure you have the (paper) gaskets for the valve body. I got mine from Automatic Berger. Note all the locations of the check ***** dropping into your face and on the floor and ensure you put them back exactly where they came from. Also get new check *****.
• Get a valve body screen and filter replacement kit (I used a TRANSGO shift kit which included the required parts)
• Clean the whole valve body.
• Be extremely careful with the plastic snap-on parts of the solenoid connectors. After having been cooked in ATM fluid for 30 years them are very brittle. I broke two and had to improvise to properly fasten them.
• The filter on the Jag is different from the standard GM part. The pan is less (?) deep AFAIR, so the standard filter won't fit. OR the pan is deeper and the standard filter is too short. Get the Jag part, and you will save yourself the trouble. SNG has the correct part.

Good luck.
G

 

Thanks for your hints. Actually I am not a car electrician so I am little lost with measuring current through a wiring harness. With a standard multimeter like I could measure over short distances, but not from the TCM in the trunk to the tranny connector under the car (probably even need to lower the tranny at the rear end in order to be able to reach out to the connector). I could use another wire as prolongation but I still would need some kind of sticky connector so I can be sure the measuring installation stays in place while I am at the other end of the car. Any recommendations on what to use here?

Regarding the line pressure I'm not sure either, can it be measured without JDS? How would you do that?

Opening of the valve body would be my second approach (third approach = new TC), if a new TCC solenoid, pressure manifold and internal harness don't fix the issue. I think even the TCC valve and spring should be exchangable without opening the valve body.

BTW: What kind of issues did you have with your 4L80e? And did you finally manage to fix them?

 

Hi V12Lover,

Here are a few tools I use when I need to connect my meter between two points that are farther apart than my meter test leads can reach. All are readily available on Amazon and ebay:

Retractable Test Leads (I have a 10-foot set by Lang and a 30-foot set from Harbor Freight):





Automotive Electrical Connector Test Adapter Kit (mine is by Electronic Specialties but there are other brands). With these pig-tail adapters I can connect banana-plug test leads to many kinds of standard male and female automotive electrical connectors:






Wire Piercing Probes (mine are by Pomona but there are other brands at much lower prices). These allow you to connect banana-plug test leads to virtually any accessible point of any wire, leaving just a pin-***** in the insulation:




Cheers,

Don

 

I don't remember if it's possible to remove the TCC solenoid without dropping the valve body. Space is very limited. It might be worth a shot. But as long has you have the TCC engaging, your solenoid is working. I would recommend to measure its resistance first. But your TCC pressure could be dropping due to a worn TCC valve.

I have slightly harsh shifting on the 2-3 gear change, which hasn't been fixed by cleaning and replacing all seals and screens. Could be a slightly leaking check ball valve.

 

Have you tried to get a flash code from the tcu?