Wanted: 3.0 Sei Speed Sensor and Amplifier Box

[xmmark]

Hi All,

I require a speed sensor and amplifier for a Series1 3.0 SEi Auto, if anyone could help with
known working units.
My cruise control works very briefly in the morning and when car is cold. At the same time my
trip computer works correctly, then within a mile or so the the cruise drops out and all speed
related data disappears and for the rest of the day it refuses to work again.
I have done as many continuity checks as I could find, there don't seem to
be any diagrams on this forum for item no 56. I have re-soldered the circuit board on the
amplifier but this didn't change anything....
If anyone is interested, I have a perfect working series 1 left display.

Greetings from sunny South Africa,

Thanks,

Mark

[White Exec]

Hi Mark, and welcome to the Forum.

Unable to help with either CC sensor or the interface, but this is the parts diagram and part numbers (all NFP)...
.

S1 cruise components.JPG

Might help track down some replacements.

I don't think we have a circuit diagram for the internals of the interface, but it could be built from standard components.
Distance (speed) sensors are quite a common failure. They are a basic hall-effect (inductive) sensor, so you might be able to check it out. Parts suggests there were two types - 2-wire and 3-wire.

If you could post your RP number (or VIN number), we ought to be able to post the exact Citroen-original wiring diagram for that part of the car, although it won't include any module internals.

[Dieselman]

Hi Mark, and welcome to the Forum.

Unable to help with either CC sensor or the interface, but this is the parts diagram and part numbers (all NFP)...
.
S1 cruise components.JPG

Might help track down some replacements.

I don't think we have a circuit diagram for the internals of the interface, but it could be built from standard components.
Distance (speed) sensors are quite a common failure. They are a basic hall-effect (inductive) sensor, so you might be able to check it out. Parts suggests there were two types - 2-wire and 3-wire.

If you could post your RP number (or VIN number), we ought to be able to post the exact Citroen-original wiring diagram for that part of the car, although it won't include any module internals.

If you have a circuit diagram it would be very welcome, use Rp 5713.

AFAIK, all series 1 hydractive cars use the same 2 wire sensor and Bitron amplifier.

To the O/p.

The 2 wire speed sensors are generally reliable, but without scoping the output it's impossible to say. Check for poor connections.

Have you noticed any issue with the hydractive system staying in soft mode and have you scanned the HA ecu for codes? iirc, Code 25 is the speed sensor.

[White Exec]

Hi Will,
Nothing here for RP5713 (30 June '92). John might have - but see below.
Earliest cruise circuit I have is RP6383 (1 May '94) - all models except 2.5 - but for a 3-wire sensor:
.

S1 3.0 cruise control _p.jpg

Might be of use in checking continuities etc.
Distance sensor (#154) is 3-wire
#60 is CC control (interface) unit
#760 is vacuum pump
#438 is CC electrovalve
#143 is suspension ECU
#214 is control stalk
#319 is brake pedal switch
#328 is clutch switch
#611 is dash switch

[White Exec]

Have just found this Hydractive I circuit, which John gave me some time ago.
Shows the 2-wire distance sensor (#154), feeding the Suspension ECU (#143), and a scrap of the sensor amplifier (#56).
.

9HY18.jpg

.
This also shows the speed (distance) sensor and interface...

9HYcH203.jpg

.
Looks as if the 2-wire distance sensor was also used on early Hydractive 2 as well...
source: H2 Presentation, No.18, 9 April 1993

9HYj03_cropped.jpg

[Dieselman]

Thanks Chris.
What I am trying to work out is if the three wire speed sensor output is compatible with a Hydractive-1 ECU.

[White Exec]

H1 circuits that I have all show a 2-wire sensor used.
Looking at the first of the H1 circuits above...
- V6 uses an amplifier module for the sensor signal, and a single feed to the susp ECU.
- the 2.0i does not use an amp, but feeds direct to the ECU with two connections.
Are these these sensors electrically identical?
Could be signal stability was an issue on the V6, but not the 4cyl.

The 2-wire sensor (with its amplifier) got carried over to H2 (see the third circuit)***.

By RP6383, the sensor was 3-wire
pin1 +12 IGN
pin2 Gnd
pin3 Output - direct to susp ECU, with no intermediate amplifier, single wire feed to pin 15B/11 on the suspension ECU.

It looks then that the amplifier (or whatever wave shaping circuit) got built into the sensor itself, which would account for it needing a +12 supply. HA Training document B7 refers to a 3-wire sensor, with +12 supply.

Because of ***, I am wondering whether the input requirements of both the H1 and H2 ECUs might be similar, and whether the output of a 2-wire sensor + its amplifier might be the same as a 3-wire powered sensor?

Don't know the answer to this. A 'scope test would reveal.

"What I am trying to work out is if the three wire speed sensor output is compatible with a Hydractive-1 ECU."
So maybe...

[White Exec]

Quick check on parts...

S1 showing 2 speed sensors:
5918 85 NFP 2-wire (showing for Xan, XMI, XMII, ZX)
96 008 163 NFP (for XMI only) Does not say whether 2- or 3-wire.

S2 shows only one sensor:
6160 70 (available) 3-wire
for all XM 2.0i and V6, and about 20 other more recent vehicles too.

[xmexclusive]

Since the early XM days the speed sensor electronics has evolved and simplified.
It is now a rotating magnet with N and S poles passing very closely a 3 wire HALL effect device.
This gives a very strong alternating magnetic field for the device to pick up and send as an AC electrical signal.
The early types of speed sensor were much cruder mechanical/electrical switches and far more prone to fault and failure.

There were quite a few early XM speed sensor drive box versions.
The earliest was a simple mechanical drive box at the gear box driving a speedo cable with an electrical speed sensor mid cable.
Output was two wire to the amplifier then signal on to the suspension ECU. (V6 arrangement).

For the 2.0i a combined mechanical/electrical box was fitted to the gearbox.
Mechanical cable speedo drive from the centre with an electric connector alongside.
3 wire connectors were standard on these even though only two wires were used.

With the advent of electric speedos on XM's (Mk 2's) no mechanical drive was needed.
Citroen took the easy way out and later caused us many service problems from early Mk 2 speedo drive boxes.
The electronics were not updated so signals were poor.
The new product was just a rubber bung to fit into the mechanical drive hole in the speed sensor box.
In service this let water in which got at both the electronics and the glue fixing the rotating magnet.

Fully sealed Hall effect speedo drive boxes common to other PSA models arrived and these should be fitted if there is no need of mechanical drive cable.

The HALL effect device is 3 wire (+ve/signal/earth) but the earth is optional and does not need to be connected for the device to work in this application.
For example Hall effect devices can also be used in ABS sensors to sense magnetic field changes.
In that application the ABS sensor is two wire and no earth is fitted.

John

[Dieselman]

Hi Both,

My query is really whether the Hydractive 1 ECU can accept the amplified signal from the later 3 wire sensors.
When a 2 wire sensor is used it either feeds directly to the Hydractive ECU, or via the Bitron amplifier, but appears to be a pass-through connection without amplification.
3 wire speed sensors are a lot easier to come by than 2 wire sensors and Bitron amplifiers, hence the interest in investigating this.
A two wire sensor and amplifier is guaranteed to work with Hydractive-1 and electronic speedometer, but I'm not sure about a 3 wire sensor working with H-1.

At some stage I'll 'scope some sensor outputs and see what the outputs are.

Interestingly, there was a bulletin regarding converting S2 cars that use Fenix-3 and Fenix-4 ECU, back to the 2 wire sensor and Bitron amplifier.