2.8 Auto Braking By Itself While Cruising To Halt

[Alex]

As title my 2.8 crd auto 2007 is braking sharp when cruising to halt, well just before coming to full stop. Also jerky when crawling traffic. Car doesn't move off when put in drive without reving on flat. Gearbox shifts through gears perfectly. I did autobox filter and atf4. Worked perfectly for last year. Could it be brake disc or caliper? Although it doesn't pull to either side under braking. No funny noises just bit clunk as if slammed on brakes just before full stop.

[Alex]

I've kept checking atf4 dip stick in park. Still in between marks

[bignev]

I am lead to believe that bugger all except a genuine Chrysler "starscan" will read the gearbox module on most of these. Certainly that's the case on my 2002 3.3 petrol.

 

However my 2005 3.3, with a different layout of ecu's, and not a separate TCM, can be read with my mates "Autel Maxisys" if I've spelt it correctly. 

It can see everything, including the individual solenoids. 

 

But it's certainly a very strange ruddy thing you've got here. A ray of hope when changing the solenoid pack, then dashed soon afterwards.

Where did you get it from? Ours is slightly noisy going in to first and reverse, so was considering a swap over.

[andyb2000]

I think you're getting somewhere, even by elimination.

 

Voltage is fine, the ECU regulates the voltage of charge anything up to 14.5v is around right so that looks fine to me voltage-wise (Beware not to take battery terminal off too much, it can cause spikes and fry ECU!)

 

I think the key here is you changed the solenoid pack, it helped then stopped again. That makes me think what you did when replacing solenoids improved things. Did you empty fluid and totally refill? I'm thinking along the same lines, have you changed the autobox filter and done a full fluid change?

 

When you drop the solenoid pack out next time I'd be changing filter and fluid completely and then potentially do that once again after a day or so (It's difficult to do a complete fluid change).

[SpAwNtoHell]

A approximate full fluid change can be done but involves disconnecting the return oil line from the oil cooler, run the engine and top up in the same time as it gets out... til fluid on return clear, that will refresh the oil cooler and most of the torque converter. Is hard to explain and a bit of a mess to do it.

[Alex]

Hi. Thanks for replies. I've had some success to early to say nailed it. Let me explain.

 

Auto Electrician squeezed me in for quick look see yesterday. His computer checked for faults, no gearbox or ecu faults. His computer was able to give live data on Transmission range sensor showing us changing gears and what each solenoid was doing. All checked fine with Chrysler service manual charts. Also showed clutch volume index or CVI for each solenoid. All within correct parameters.

L/R cvi 75

2nd/4th cvi 20

O.D cvi 68

Low gear cvi 35

All of this with car on and in reverse with fault present.

 

The only bad thing we notice was transmission temperature sensor/TTS said -20C 1.8V . Outside temp on day was 12C so obviously wrong. This sensor is built into transmission range sensor, got pull gearbox apart to change and not readily available. These sensors work on very small changes in voltage which can also occur with bad connection/corroded terminals or bad ground.

 

I've unplugged every plug sprayed electric contact cleaner, cleaned up and Replugged. I also removed TCM from under passenger wheel arch. Opened it up. It's computer pci board in clear jelly. Jellies still crystal clear no sign of green corrosion or blackened short so think its fine. Didn't touch anything just closed it back up. Mine has Mopar remanufactured sticker on it. P/N R4727535AF. What I did do is turn it over and file mounting area that touches car body as this Tcm is ground on case. Been aluminium body another corrosion bad contact area for ground. I'm starting to think most problems on these voyagers are bad connections and bad grounds/negative. I also ran wire from negative battery to back of this Tcm case traped by mounting bolt.

 

Finally found the TCM relay! On 2.8crd 2007 if you open bonnet in front of fuse box and ecu above radiator you'll see 5 or so black box's mounted on front beam. First three from left are radiator fans relays then TCM relay and far right is lighter grey is glow plug relay.

I found TCM relay abit green corroded, cleaned and swapped with one rad fans. Reassemble car tes t drive time. We'll if you've read all this let me give you good news, car seems nearly right. Gear shifts are abit abrupt not as smooth as before but I'm thinking gearbox might need to relearn.

 

Side note. I preformed an autopsy on old solenoid pack. Check with ohm meter coils all showed continuity so they where fine, 3 x sensors showed 250ohm each if remember right which seemed right. I then pulled 8 x tiny filter out. Each was spotless clean and mesh was white. Atf4 oil that came out rose light pink. I then un screwed and split unit. Didn't find any debri,back of coils was slightly grey. My verdict. Gearbox hasn't got blockage from debri in hydraulics. Don't think the old solenoid pack was bad. Don't regret spending £102 on brand spanking new one. Might still have to bite bullet and drop pan to check filter. Changed filter and 4l mopar atf+4 at 116k it's on 122k now. From records last changed by chrysler dealer 88k. Records also show Recon gearbox fitted 66k with new solenoid pack.

Edited April 28, 2018 by Alex

[Alex]

Heading back to Auto Electrician this week to check results on Transmission temp sensor and further alternator test. Also bought two new mopar relay and their sockets to replace that corroded TCM socket and relay, £30 on eBay.

[bignev]

I shall be keeping my fingers crossed on it for you Alex!!

Thanks for the jolly good write up mate.

 

And a good result finding a guy with kit clever enough to see the TCM - awesome that.

[andyb2000]

Definitely sounding hopeful and yes holding my breath for you, thanks for replying back some really good information there to help others if they have issues with their transmission.

BTW not wanting to turn this into a selling page but can you post the auto electricians location/fb page or similar, he sounds a handy guy for the community.

[Alex]

Hi guys.

 

Dare I say cars fixed. Done some local running around and 100mile round trip yesterday, no hiccups.

 

Unfortunately lost out on relays on eBay, guy refunded me said he'd sold them already. Bummer.

 

Haven't been back to Auto Electrician, he's to busy. I'll happily give his details but should say he knows nothing about these cars which he informed before I got there. He was helpful in trying all his gear to get me computer readings. I printed wiring diagrams,plug details, gear selection charts and graphs to be able to compare to any data he could retrieve . I photoied readings as came up on his pc so could look at details later. He was the one who spoted thermostat reading. All in nice accommodating bloke,cost me £40 so not bad.

https://www.diagnosticman.co.uk/

[SpAwNtoHell]

good to hear that is fine, temp sensor seems that done it? i was looking today through the workshop manual and on this voyagers seems like also coolant sensor faulty gives also the same behaviour. Side note 250 Ohm is very high for the solenoids as far as i checked... maybe you miss spelled?

[bignev]

Hiya Alex, if you let me know what the code is on the relay, I have a spare fuse box that might have some in, if so if you cover the post you can have them.

[Alex]

Thanks for very kind offer Bignev. I've bought secondhand fuse box to scavenge parts now.

 

You're right Spawn. Probably decimal places which I missed glancing at meter. What i took from it was three sensors resistance matched which normally means okay. I'll check again and put each reading for accuracy sake.

 

Thanks for comments.