Dear All,
Just a note to show you how important the BoK is, as you know the TEMS on our Townie was screwed up by the alarm fitter, I needed the wiring colour codes & posted a request for info. Hey presto two of you came to my rescue, using some chock block to replace the knackered connector the problem is now solved & we no longer have 'rock n roll' on cornering. So a special thank-you to John Davis & Ian Dunse who sent me the words & diagrams that allowed me to cure the problem, thans guys.
Regards Rob. - (#2570) Rob Drinkwater, 27 Mar 02
I can now see that the wires ("TEMS, please help") appear to go in a grey sleeve down round the steering column to a sensor(?) on the left hand side below most other things. This bit of TEMS doesn't seem to work on mine though, TEMS only switches with the brakes. Does this steering sensor just switch when the steering is turned by a certain angle? How big an angle? Why 4 wires? Anyone know what test results to expect on either of those connectors? - (#2625) Dave Mason, 2 Apr 02
Dave,
Tricky one this, whilst trying to work out which wire went where, I thought that the steering column sensor must just be one, maybe two potentiometers that sent a resistance value back to the TEMS ecu, this would then interpret this as a steering angle then compute that angle vs speed to decide when to go 'hard' & when to stay 'soft' this in mind I tried measuring the resistances on the four wires, to my surprise there was no change in resistance across any of the wires, suggesting that this isn't the way the sensor works. I then tried testing the wiring coming in from the TEMS ecu, this appears to have one wire that is earth, one with 3volts, one with 5 volts & one with 6 volts. So I was still no nearer working out how this all works. I can only assume that the voltages coming into the column sensor change when the vehicle reaches a certain speed and then the column sensor will come into it's own. So in essence I can't help you with resistances or voltages, as, despite trying to work out how it all works & extensive playing with this system I haven't got to the bottom of the system. Regards Rob. - (#2627) Rob Drinkwater, 2 Apr 02
Thanks, Rob, for reporting as far as you got investigating the TEMS steering sensor.
Since you have the valuable experience of driving both with and without it working, can you describe what effect it has (for someone like me who is trying to get it working). Is there a certain amount to turn the steering wheel to get the TEMS "hard" light on? And how does this amount depend on speed? Some rough guidelines would help. It must be fairly sensitive because I find that on most corners the TEMS goes hard anyway because I'm touching the brakes (with Auto box).
Also, where is the TEMS ecu? - (#2675) Dave Mason, 8 Apr 02
Dave
Fortunately I haven't had the pleasure of driving without TEMS. I can say that at speed you only have to nudge the wheel or touch the brakes to get the "hard" light to come on . The ECU appears to be under the steering column to the right of the steering sensor - a square box shape.
Ian - (#2678) Ian Dunse, 8 Apr 02
Sorry guys, I hadn't scrolled down as far as this for a few days, so missed the further posts on this subject. As regard the effect of not having TEMS, it only really manifested itself when I had to swerve around a car that pulled out in front of me, I noticed how much the van rolled from side to side, infact we thought she was going to end up on her side. I thought that the body roll seemed a bit excessive, so I went to the next roundabout & progressively went faster & faster but no 'hard' light & lots of body roll. Upon investigation I found the plug apart, but that's another saga. I would say that the ECU must work out that the faster you go, the less amount of turn it needs to engage 'hard' i.e. low speed you need to steer quite hard, high speed only a slight turn is required, but I also think it depends how sharply you turn the steering, a gentle turn & it doesn't go 'hard' but tug the steering a la evasive action & it goes over to 'hard' very quickly. The ECU seems to be under the steering column. I assume the vans without TEMS have a suspension system that is set somewhere between the 'soft' & 'hard' positions as a compromise, but the TEMS is designed to be a 'transparent' aid to driving, and having missed it whilst not working, I wouldn't be without it now, the whole vehicle now feels much more stable & we can throw her around with confidence. Regards Rob. - (#2692) Rob Drinkwater, 8 Apr 02
Sorry guys, I hadn't scrolled down as far as the other posts on this subject. As regard the effect of not having TEMS, it only really manifested itself when I had to swerve around a car that pulled out in front of me, I noticed how much the van rolled from side to side, infact we thought she was going to end up on her side. I thought that the body roll seemed a bit excessive, so I went to the next roundabout & progressively went faster & faster but no 'hard' light & lots of body roll. Upon investigation I found the plug apart, but that's another saga. I would say that the ECU must work out that the faster you go, the less amount of turn it needs to engage 'hard' i.e. low speed you need to steer quite hard, high speed only a slight turn is required, but I also think it depends how sharply you turn the steering, a gentle turn & it doesn't go 'hard' but tug the steering a la evasive action & it goes over to 'hard' very quickly. The ECU seems to be under the steering column. I assume the vans without TEMS have a suspension system that is set somewhere between the 'soft' & 'hard' positions as a compromise, but the TEMS is designed to be a 'transparent' aid to driving, and having missed it whilst not working, I wouldn't be without it now, the whole vehicle now feels much more stable & we can throw her around with confidence. Regards Rob. - (#2693) Rob Drinkwater, 8 Apr 02
Mine hasn't got TEMS and after 2 weeks on Irish roads I can safely assure you non TEMS suspension is set up quite hard! - (#2703) SteveFE, 9 Apr 02
I've had my '91 Townace 4WD Auto nearly a year and realised from BoK postings that its TEMS steering input was not working. I think I've fixed it now and here, for the record, is what I found.
To access the steering sensor remove the cover from the steering column (3 screws at the bottom edge). The sensor is a black plastic box held to the left side, below all the wiring, by two crosshead bolts. One of these bolts is awkward to get out and in my case already had the head badly chewed, probably for that reason. Removing another trim panel might have helped. The wiring to the sensor has a 4-way connector higher up, to the right of the column. It is an electronic unit and the wiring carries earth, a supply of about 5v and two return signals around 2v. These are low-current connections which on the one hand need care when testing and on the other hand are very susceptible to bad connections such as, I guessed, mild corrosion while the vehicle was laid up during importation.
The sensor has two photosensors (light, or infra-red, emitting diodes and detectors). Between these revolves a metal disc, in which there are about 20 holes, fixed to the steering column. Inside the sensor case, which can be opened easily, there is a small printed circuit board on which the photosensors and 3 other components are mounted. It appears to me that output of the two photosensors is fed straight back to the TEMS computer giving information about the angle, speed, and even direction of rotation of the steering column. Sophisticated stuff.
In my case a bad connection between the wiring and the sensor circuit board was affecting one of the return signals. Slightly wrigging the connector there appeared to fix it although final testing is not straightforward since you have to get out and drive at 20+mph to get a result.
- (#3242) Dave Mason, 5 Jun 02