607 4HP20 auto trans temp sensor fault and other issues

dieselnutjob · Unread post by **dieselnutjob** » 16 Jun 2010, 23:00

My Peugeot 607 HDI auto has had an intermittent transmission sensor fault on it I think ever since I owned the car.
Today the gearbox acted very strangely, which it hasn't done before, and the intermittent sensor fault went permanent according to Peugeot Planet 2000.
As I was driving home from work the gearbox started holding higher revs than it normally does before changing up. The tiptronic mode still worked normally.
I didn't get any dashboard error messages.
After a while I decided to stop and turn the ignition off and restart, a reboot if you like.
Now I found that the tiptronic mode would not engage, so with the gear lever pushed over to the left the dash still said D instead of M and pushing it backwards/forwards had no effect.
When I got home I put the PP2000 on and found that the ECU was picking up selector position normally, mode was "ECO" and everything seemed normal. However I now had a permanent temp sensor fault and an oil temp of 120 deg C.
I left the car to cool down with the bonnet up and went and had some tea and put kids in bed etc.
Now the permanent fault is still there, but oil temp was down to 60 deg C and the car drives perfectly again.
I drove a couple of miles and temp got up to 95 deg C. Not sure if it was still climbing or not.
I will have a look at the wiring tomorrow, but from the wiring diagrams I'm not sure which signal is the temp sensor.

The wiring diagrams are here:-
(open them with Firefox, or with Adobe SVG viewer plugin to IE)
http://christiantena.pwp.blueyonder.co. ... ciple.svgz
http://christiantena.pwp.blueyonder.co. ... iring.svgz
http://christiantena.pwp.blueyonder.co. ... ation.svgz

Currently I suspect that the sensor is kippered because the engine temp sensor did a similar thing in the autumn (it worked normally upto about 90 deg C and then went nuts).

I also suspect that getting to that temp sensor is not nice

dieselnutjob · Unread post by **dieselnutjob** » 16 Jun 2010, 23:04

on my Firefox installation (actually iceweasel) clicking on those links above directly doesn't work.
You have to right click and select "Save Link As"
Then save the file on your desktop / harddisk etc
Then right click the file and do "Open with" and select firefox
Might work better on Windoze or Mac though....

dieselnutjob · Unread post by **dieselnutjob** » 17 Jun 2010, 19:32

found some info on page 114 here
http://www.matrasport.dk/Cars/Espace/va ... aining.pdf

dieselnutjob · Unread post by **dieselnutjob** » 17 Jun 2010, 20:45

that doc has been invaluable
it tells me that pins 21/22 on the transmission ECU are connected to 4/9 on the transmission connector which connect to the sensor inside.
I checked the loom and it checks out as 0 ohms for each wire.
across 4/9 I'm getting 1620 ohms which is too high for a warm gearbox according to the charts in there.
Also it tells me that the ECU defaults to 120 deg C if it can't see the sensor, which is what I was getting
I will leave the car overnight and see what the sensor resistance is cold.
Bad news is that the sensor is part of the transmission internal wiring harness so I'll probably have to change the entire harness

jgra1 · Unread post by **jgra1** » 18 Jun 2010, 09:35

good that your getting somewhere with this dieselnutjob

hope you dont have to harness change...

John

dieselnutjob · Unread post by **dieselnutjob** » 18 Jun 2010, 10:22

the resistance was 945 ohms this morning which is right where is should be for about 20 deg C ambient temp

now I'm not so sure that it is the sensor

maybe the ECU is kippered

wonder how I can tell

Unread post by **CitroJim** » 19 Jun 2010, 12:25

Yes, the sensor is part of the harness but changing it is an ordeal. The sensor pokes down a slanted hole in the valve block and it's tight in there. It's also on the base of the valve block.

I doubt you'll do it in-situ. One hopes it might be possible to remove the valve block without lifting the whole power train.

If the sensor resistance you measured looked wrong then the ECU is most likely OK. It's rare for an ECU to fail and much more common for a thermistor to do funny things.

Before condemming the sensor or the ECU, do check the oil temperature independantly just in case the proble is telling the truth and you have some other malfunction causing the oil to get very hot.

spider · Unread post by **spider** » 19 Jun 2010, 13:18

Good call about checking the temperature with other means just to be 100% sure.

Looking at that .pdf , although I have not got involved at all with these (after my 'time' as it were) , it does as Jim says look a fairly major job to get that sensor out.

dieselnutjob · Unread post by **dieselnutjob** » 19 Jun 2010, 15:51

the next thing I'm going to do is buy a 2k potentiometer and connect in place of the sensor
then I can observe what the ECU says whilst varying the resistance.
It will hopefully tell me whether the ECU is picking up the signal or not.

dieselnutjob · Unread post by **dieselnutjob** » 22 Jun 2010, 20:53

CitroJim wrote:Before condemming the sensor or the ECU, do check the oil temperature independantly just in case the proble is telling the truth and you have some other malfunction causing the oil to get very hot.

Do you think pointing this at the transmission would tell me anything?
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0619630053

h2ocooler · Unread post by **h2ocooler** » 22 Jun 2010, 21:13

The temperature

but seriously yes it would tell you the temp of the case/sump, might not be 100% but will give you an idea.
Rob

dieselnutjob · Unread post by **dieselnutjob** » 27 Jun 2010, 17:16

Today I unplugged the loom from the top of the transmission, and plugged a 2k potentiometer in its place. Then I turned the ignition on and monitored transmission temp whilst twiddling the potentiometer.

The ECU did stop registering the reading and went to a what appears to be a default temp a few times, so I'm actually thinking that its probably the ECU that's at fault.

I have also realised that if you want to you could monitor gearbox temperature by monitoring the voltage across the sensor. I am thinking a discrete LED display somewhere on the dash would be useful for towing.

The voltage across the sensor is
temp voltage
-30 1.10
-20 1.19
-10 1.27
0 1.36
10 1.43
20 1.51
30 1.59
40 1.67
50 1.76
60 1.85
70 1.93
80 1.99
90 2.07
100 2.15
110 2.23
120 2.30
130 2.38

dieselnutjob · Unread post by **dieselnutjob** » 27 Jun 2010, 18:40

Think I'm going to buy a MAX1496, some seven segment LEDs and a couple of opamps and knock myself up a dashboard transmission temperature monitor.

I'll use it to monitor the difference between pins 21 and 22 on the transmission ECU.

If the numbers go nuts when I'm driving along then I have a wiring or sensor issue. If the numbers are sensible but the ECU goes into paranoid mode then I'll know that I have an ECU fault.

And it'll be useful to keep an eye on the transmission anyway, and for doing oil changed as well.

spider · Unread post by **spider** » 27 Jun 2010, 21:16

You could do with something that will record any sudden temporary fluctuations too (I'm thinking if it suddenly spikes to one extreme or the other for half a second or so you'll probably not notice it)

I wonder what would happen if you got one of those LCD temperature monitors (with an external probe) the ones that are only a few £ as they can remember min / max values.

You may be able to plug it in alongside your existing temp sensor (into its wiring) the readings on the LCD will not correspond with what is going on in the transmission but at least if you 'test' the lcd to determine 'real temp' = x on the display you will know.

That might be too much trouble though, if you get get a latching circuit to catch any odd behaviour you`ll probably do just fine.

Unread post by **CitroJim** » 28 Jun 2010, 08:31

dieselnutjob wrote:Think I'm going to buy a MAX1496, some seven segment LEDs and a couple of opamps and knock myself up a dashboard transmission temperature monitor.

Hat fairly and squarely taken off to you on that. Excellent stuff!

I'm working on an allied project to measure gearbox oil pressure. There's a convenient test point in the main gallery from the pump and we're hoping the readings may help indicate when the filter is becoming clogged.