Steering wheel functions module circuit diagram
Discussion
Hi clever folk, has anyone reverse engineered the steering functions module please.
The R4 resister has let out the magic smoke, trying find out its value. I may have inadvertently pushed the ribbon cable in reverse 😢
If not a photo may help to see the colours. A circuit diagram would be brilliant. TIA.
The R4 resister has let out the magic smoke, trying find out its value. I may have inadvertently pushed the ribbon cable in reverse 😢
If not a photo may help to see the colours. A circuit diagram would be brilliant. TIA.
CER927 said:
Hi clever folk, has anyone reverse engineered the steering functions module please.
The R4 resister has let out the magic smoke, trying find out its value. I may have inadvertently pushed the ribbon cable in reverse ?
If not a photo may help to see the colours. A circuit diagram would be brilliant. TIA.
No circuit diagram unluckily but I do have lots of photos and a spare unit The R4 resister has let out the magic smoke, trying find out its value. I may have inadvertently pushed the ribbon cable in reverse ?
If not a photo may help to see the colours. A circuit diagram would be brilliant. TIA.
Measuring the resistance across R4 is appears to be 10.2 Ohm and the colours as far as I can see are Brown, Black, Black, Gold which matches what a 10 Ohm resistor should be
Any more photos or measurements you need just let me know
Juddder
Thank you Judder, I (we) have had the steering wheel/column out this morning. I discovered that one of the hazard warning switch wires had been pulled out of its connector . A quick solder by a more competent friend, and then gently returned back into the car and hey presto, hazard warning lights are now working again. I also have indicators, horn, dim dip, washers and wipers working. So I am at a loss, as to what the burnt resistor does. Perhaps it is not completely kaput?
Pleasure and great that you have it all working again.
Often resistors are just used to stabilise bits of circuit so it might not be a critical component to getting the unit running (no schematic, just a logical guess )
If you meter across the resistor with a multi-meter on ohms setting you can see if the resistance is infinite (blown) or around 10 Ohms (still working) which will give you the heads up as to whether it is completely kaput or just wounded from (at a guess) have excess current going through it due to being grounded or similar
Often resistors are just used to stabilise bits of circuit so it might not be a critical component to getting the unit running (no schematic, just a logical guess
)If you meter across the resistor with a multi-meter on ohms setting you can see if the resistance is infinite (blown) or around 10 Ohms (still working) which will give you the heads up as to whether it is completely kaput or just wounded from (at a guess) have excess current going through it due to being grounded or similar
Seeing as I had the spare Steering Wheel Control Box out, I photographed and measured all of the other resistors so we all have it for reference
R1 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R2 - 7 K Ohm = ?, ?, Black, Gold, Gold (Couldn't match the colours on this one but the values metered consistently at 7 K Ohm)
R3 - 1.2 K Ohm = Brown, Red, Black, Brown, Brown
R4 - 10 Ohm = Brown, Black, Black, Gold
R5 - N/C
R6 - 10 K Ohm = Brown, Black, Black, Red, Brown
R7 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R8 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R9 - 1.2 K Ohm = Brown, Red, Black, Brown, Brown
C2 - 1J63 - 1 uF, 5%, 63V plastic film capacitor
C4 - 33J63 - KEMET R82 Polyester Film Capacitor, 40 V ac, 63 V dc, ±5%, 330nF, Through Hole
C5 -
C6 - 10nJ100 - AV 100V 103 0.01UF 10NF 10nJ100 103J 5% R82 Correction capacitor
IC3 - ST Microelectronics ULN2803A - Eight Darlington Arrays
RESNET1 - Bi L81S 103 536
RESNET2 - Bi B99-3-R 220K - Dual-In-Line 220K Resistor Networks
R1 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R2 - 7 K Ohm = ?, ?, Black, Gold, Gold (Couldn't match the colours on this one but the values metered consistently at 7 K Ohm)
R3 - 1.2 K Ohm = Brown, Red, Black, Brown, Brown
R4 - 10 Ohm = Brown, Black, Black, Gold
R5 - N/C
R6 - 10 K Ohm = Brown, Black, Black, Red, Brown
R7 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R8 - 100 K Ohm = Brown, Black, Black, Orange, Brown
R9 - 1.2 K Ohm = Brown, Red, Black, Brown, Brown
C2 - 1J63 - 1 uF, 5%, 63V plastic film capacitor
C4 - 33J63 - KEMET R82 Polyester Film Capacitor, 40 V ac, 63 V dc, ±5%, 330nF, Through Hole
C5 -
C6 - 10nJ100 - AV 100V 103 0.01UF 10NF 10nJ100 103J 5% R82 Correction capacitor
IC3 - ST Microelectronics ULN2803A - Eight Darlington Arrays
RESNET1 - Bi L81S 103 536
RESNET2 - Bi B99-3-R 220K - Dual-In-Line 220K Resistor Networks
Edited by Juddder on Saturday 13th September 19:12
R4 is connected to pin 7 on the main 10 pin ribbon cable output, and that is +12V output, so I guess that justifies the thicker track
For CER927 if something shorted in his steering wheel column, and the +12V went to ground, I'm guessing that would take out R4 with the higher current flowing straight through the resistor
The +12V in the Steering Column is used to power the Optical Sensors that are used to cancel the turn signal, so if the indicators were the problem, which they are here, it could have caused the above
I spent sometime documenting my one of these when it blew, so here's as far as I got with the pinout which will hopefully help your KCad reverse engineering (*which is great to see BTW)
Alex
For CER927 if something shorted in his steering wheel column, and the +12V went to ground, I'm guessing that would take out R4 with the higher current flowing straight through the resistor
The +12V in the Steering Column is used to power the Optical Sensors that are used to cancel the turn signal, so if the indicators were the problem, which they are here, it could have caused the above
I spent sometime documenting my one of these when it blew, so here's as far as I got with the pinout which will hopefully help your KCad reverse engineering (*which is great to see BTW)
Alex
Steering Wheel Functions Control Unit
A1 - N/C
A2 - HEADLAMP SIGNAL (A1)
A3 - N/C
A4 - N/C
A5 -
A6 - WIPER 2 SIGNAL (A6)
A7 - MAIN BEAM SIGNAL (A0)
A8 - DIP BEAM SIGNAL (D13)
A9 - TURN LEFT SIGNAL (D10)
B1 - IGNITION
B2 - HORN DRIVE (A2)
B3 - HAZARD DRIVE (A3)
B4 - BATTERY
B5 - GND
B6 - WIPER 1 SIGNAL (A7)
B7 - N/C
B8 - WASHER SIGNAL (D12)
B9 - TURN RIGHT SIGNAL (D10)
10 Pin Ribbon (labelled right to left when looking at the back of the unit, pins in front of you)
10 - GND
9 - CANCEL RHT IP (D9)
8 - CANCEL LEFT IP (D8)
7 - +12V
6 - N/C
5 - N/C
4 - HORN INPUT (D7)
3 - DIP INPUT (D6)
2 - WASHER INPUT (D5)
1 - WIPER INPUT (D4)
5 Pin Ribbon
5 - N/C
4 - HAZARD W/L (D3)
3 - HAZARD SWITCH (D2)
2 - INDICATOR RIGHT (D0)
1 - INDICATOR LEFT (D1) Silver pins up RHS
Edited by Juddder on Wednesday 17th September 08:55
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