I'm trying a new subject line because my "dumb question" title didn't elicit any replies

Can the emergency brake make the transmission malfunction? (2000 XK8)

I took the car out today and as I drove out of my driveway it held onto first gear up to about 2500 rpm and wouldn't shift. As I got out on the main road it upshifted and seemed fine.

Returning from the store it did the same thing. I stopped for gas and checked under the hood and everything seemed fine.

As I pulled out of the station it actually free rev'd while in Drive and as I let off the gas it engaged like a "neutral drop."

I noticed the emergency brake light was on (the brake was not dragging) and so I completely released the emergency brake.

I drove the car a lot after that and the trans didn't act up at all.

I'm hoping maybe the e-brake had something to do with the trans acting up.

Probably a dumb question, but one can hope right?

Thanks,

Tom

 

Tom,

There just isn't any way the e-brake could have anything to do with what you experienced. I'd suggest having the engine and trans systems interrogated for fault codes to see if there might be anything there to point you in some direction.

Cheers,

 

The first indicator in a free rev and drop in gear with rev decrease is low fluid level. Get it checked quickly. When the fluid is low, high revs in the pump pulls the pickup dry and the pressure drops on the clutch pistons, losing the drive. As the rpms drop, the fluid flows back to the pickup and pressure is restored.

 

Would it be advisable to change all the transmission fluid at this point?

I've read that the Jag fluid is expensive, is there a (dodge) equivalent that is suitable?

Thanks!

Tom

 

Personally, I'd want to get to the bottom of what's going on first. You do not say the mileage, but if you don't have 150,000 miles on it, and it hasn't been leaking, I'd leave the fluid alone. Of course, you will find others here who will disagree with me in that.
The reason I suggest have the codes read, is that what you describe could be just the rotary switch on the side of the trans, or it's adjustment. It could also be low fluid as oldmots mentioned. I just like to get as many facts as possible before I attack.

Cheers,

 

Tom-
check the sticky thread (xk8-xkr-frequently-asked-questions-diy-repair-maintenance) link on the forum. Lots of info on transmission and ATF issues there.

 

Gents:

I had the fluid and filter changed and it was fine for a couple of weeks. This morning, on a cold start out of the driveway, I had the same condition return. A little free rev at first and then it held onto first gear as I drove down my street. Once it did upshift it was fine for the rest of my drive around town.

Any additional ideas/suggestions?

Thanks!

Tom

 

Is it 'slamming' into gear when you are trying to get started? How long do you let the car warm up, and transmission circulate fluid before trying to take off from the house?

 

Matt,
It doesnt "slam" into gear. I let it warm up long enouhg for the fast idle to settle down and to drop the convertible top down, probably 30 seconds. Reversed out of my parking spot, put it in forward (no slam). Stopped at the end of the driveway to check traffic. When I went to pull out of the driveway it free rev'd for a second and as i let off the gas it engaged. Drove down the block and it held first gear up to 2500 RPM. As I proceeded it upshifted and everything was fine.
Thanks,
Tom

 

I'm still hangin' my hat on the rotary switch or its adjustment; at least until it is checked and verified. Doesn't sound like it's going into default, which is where I think you were going, Matt.

Cheers,

 

Thanks Steve,
Is there a thread somewhere that describes how to adjust the rotary switch? Or how to replace it?
Thanks,
Tom

 

I'm curious, to eliminate the rotary switch as the culprit, meaning it is having a problem deciding to stay in D or up just a hair into N, would putting it over into the right, selecting 3 or 4 and seeing if the condition persists on your first leg of the drive, would that take the switch out of loop, or is the manual side simply an extension of the D setting?

The symptom is making me think torque converter clutch...but I like to think big.

 

Here is what you need to adjust, replace or test the rotary sw. [Range Sensor]

Matt makes a good point about selecting D3 first, then moving back to drive. If it always drives out OK by doing that, it hints that the cable adjustment or the switch is the culprit. I have used that sequence to help confirm things many times.

Geez Matt, torque converter??? Don't scare people with that kind of talk!

Cheers,

 

Thanks Matt - Steve,

I'll try starting out in D3 for awhile to see what happens. Problem is it has been an intermittent issue all along. I'm now understanding how the rotary switch and/or adjustment might cause the free rev but could this also make it hold on to first gear/not upshift?

I'll study the pdf's too. Thaks for these!

Tom

 

Looking at you steve for an expression of agreement, now looking back at my screen and keyboard and gonna type this reply ... I don't see how the rotary switch would prevent an upshift once on its way. A hesitant initial takeoff, possibly, but surely not the next gear.

 

that is not the rotary switch i can promise you that. that does sound like a transmission problem. Now when you changed the transmission gasket and replaced the fluid did you or the thechnician follow the proper procedures. that fluid have to be at a certain temperature for you to check.

 

Thanks Nine7
I'm not sure if the tech checked the fluid at a certain temperature. Could this be causing the issues I'm describing?
Thanks!
Tom

 

absolutely, the torque converter clutch works off of a specific pressure from the fluid to apply and disengage, if there isn't enough, or too much fluid, that pressure may not be there to make the gear change. I'd double check it, at the right temperature. If you don't have a scanner that reads the fluid temp from the trans sensor, then I would suggest letting the dealer or an indy with such equipment do that little check for you. Otherwise, you're counting on an IR gun, pointed at a small stream, or drips of fluid (if its coming out the hole, and cooling immediately on its way to freedom) or the pan, which is pretty close, but not exactly the fluid temperature on the other side.

 

Thanks Matt,
I'll check the sticky threads for the trans temp check procedure (unless you can point me to it easily). I "graduated" from my local garage, who's worked on a lot of my Jags, to a guy who works mostly on high end imports (but I think he favors Italian cars over the Jags!)
Tom

 

Dang, Matt, you posed a really good question.......I had to ponder that a while to decide how to answer.

The best I can do is reiterate that the 5HP24 is a fully electronically controlled transmission. The shifter for instance, is only an input to the TCM for driver demand. It's only other purpose is to at least give you a way of selecting forward or reverse, if the TCM can't control anything and you are in default operation. On to the rotary switch or Range Sensor.

The Range Sensor uses a series of individual switch tracks to signal a gear position. These switches open and close in varying combinations to basically form a DIGITAL input to the TCM. This is old school, mechanical instead of transistors, but still digital, off or on, a one or a zero. The TCM makes its decisions based on the various inputs, speed sensors etc. Like anything electronic, [some call it fu**in' magic] if it sees an ILLOGICAL input, all bets or off. Who knows what the control response will be. Let's say one of those rotary sw. tracks goes from closed, to a low resistance instead of open circuit. The TCM EXPECTS a closed circuit or infinite resistance. That becomes an illogical input, the TCM then responds sometimes in a manner that we can't predict. Usually modules work at it until they either are back on turf they recognize, so to speak, or have crossed a condition that they recognize as a fault, and take whatever action they are programmed for in that instance.

Ever had a bad ground in a tail light? That's an unexpected resistance in a circuit that makes strange things happen; like the light on the RH side flashing dimly with the LH turn signal.

Electrons are funny things..........