Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Suspension down plea for help - no power to compressor
Hi All,
I have a 54 D3 with suspension on bump stops. I've done some investigation today and concluded the following, but am a little stumped with my next step. Appreciate some advice please?
Compressor does not run, even with IID plugged in and set to raise suspension.
I have power at Fuse 26E (20A) and 35P (5A). I have no power at 3E (5A), nor at compressor connector C0780-1. I have voltage at only one of the relay pins. I have no voltage at the relay coming fro the onboard computer. I can jump the relay with a wire and the compressor runs ok.
Why would the suspension control module not direct the compressor to run?
I have all wheels off, all wheel linings out and front bumper off. Connections look to be ok to valve block front and rear, and to any wheel arch connections. Should i pick up some continuity tests somewhere?
New valve blocks? Control Module?
Error messages:
Suspension
C1A08-1C (AF) Pressure sensor supply - General electrical failure - circuit voltage out of range
( at 149122 km )
C1A37-01 (AF) Front cross-link valve - General failure information - general electrical failure
( at 149122 km )
C1A03-1C (AF) Front left height sensor - General electrical failure - circuit voltage out of range
( at 149122 km )
C1A04-1C (AF) Front right height sensor - General electrical failure - circuit voltage out of range
( at 149122 km )
Transfer Case
U0132-86 (2F) Lost communication with ride level control module - Bus signal/message failure - signal is invalid
( at 149122 km )
U0122-87 (2F) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( at 149122 km )
Appreciate any advice please.
Thanks
Mike
8th Dec 2018 5:55 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
at a guess if
Quote:
C1A08-1C (AF) Pressure sensor supply - General electrical failure - circuit voltage out of range
If it doesn't know the air pressure, how does it know to turn the compressor on or when to turn it off.
So it acts safely and doesn't even bother to turn the compressor on
check pressure sensor wiring.
clear codes and see if the this one comes straight back
8th Dec 2018 6:14 pm
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Quote:
If it doesn't know the air pressure, how does it know to turn the compressor on or when to turn it off.
So it acts safely and doesn't even bother to turn the compressor on
Thanks Pete
Very good point. I think that should be my first port of call. Reservoir control valve, and wiring back to Air Suspension Control module through C2293 & C2294.
If all tests out i can get a 2nd hand valve.
I've read that the Suspension Control module is behind the instrument cluster, driver side. Do you know if it is easily accessible?
Thanks
Mike
8th Dec 2018 6:47 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
Don’t know about the control unit.
8th Dec 2018 7:35 pm
Sea Raider
Member Since: 01 Nov 2016
Location: None
Posts: 4450
For some reason my electronic manual isn't opening images but heres the write up in relation to the control module
Click image to enlarge
8th Dec 2018 7:58 pm
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Thanks all.
Will have a check on this tomorrow - if the wind and rain stops!
Mike
8th Dec 2018 9:47 pm
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Had a little time to look at this today.
Located suspension control module in drivers side footwell, but haven't touched it yet. Located the pressure sensor on the reservoir valve and checked the connector. Can't see any issue with the wiring in terms of breaks and frays.
Plug has 3 wires, yellow and black (PRESSURE_5V), orange and grey (PRESSURE_SIG), yellow and pink (PRESSURE_GND) as per the wiring diagram.
PRESSURE_5V tested with a voltmeter as approx 12v
PRESSURE_GND has continuity to earth
PRESSURE_SIG i'm not sure how to test. Doesn't appear to carry a voltage.
I am wondering if the label PRESSURE_5V means this should carry 5volts not 12?
I need some longer leads to do end to end continuity testing but the voltage worries me.
Cheers,
Mike
9th Dec 2018 7:25 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
Yes I believe it should be 5v.
I did wonder if it was a reference problem what with the other sensor fault codes
Measure between 5v and PRESSURE_GND.
The 0v is usually 0.5v on the height sensors
5v usually 4.5v
SEN is the sensor OUTPUT from the sensor when plugged in. Should be between 0.5 - 4.5v depending on pressure WHEN IT HAS THE CORRECT SUPPLY VOLTAGE!
Try messuring the 3 wires on a front height sensor and see if they are also 12v not 5V
Probably best to unplug that ecu to prevent damage to sensors
9th Dec 2018 7:42 pm
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Thanks for continuing to follow this.
I will check the front height sensor voltage. I note that they have flagged up in my ECU faults and the IID shows the height is not being read correctly from them. The rears seem to be giving correct readings as the value changes as i move the sensor. I will compare front and rear values.
Will do this tomorrow. Haven't built a garage yet so i'm doing his in the elements!
9th Dec 2018 8:41 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
You could also disconnect the ecu and then check the 5v at pressure sensor. . If it’s still 12v the wire has shorted some where.
Otherwise it’s the ecu
10th Dec 2018 1:49 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13595
Hi matchermike
Hope I’m not sticking my nose in as I know the guys here are extremely knowledgeable and can guide u better than myself
But was wondering if these links may be of any use to u
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1780
MatcherMike, you only get voltage at fuse 3E when the relay operates, so if relay is not operating then no volts. Have you tried swapping the relay as they are known to fail
10th Dec 2018 5:31 am
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Thanks for the replies.
Quote:
You could also disconnect the ecu and then check the 5v at pressure sensor. . If it’s still 12v the wire has shorted some where.
Otherwise it’s the ecu
Great idea. I'll test this.
Quote:
Hi matchermike
Hope I’m not sticking my nose in as I know the guys here are extremely knowledgeable and can guide u better than myself
But was wondering if these links may be of any use to u
Not at all thanks for the links. I'm slightly nervous i've bitten off a little bit more than i can chew, but i love the car so really want to get this sorted. I'll try anything and everything anyone can suggest to resolve.
Quote:
MatcherMike, you only get voltage at fuse 3E when the relay operates, so if relay is not operating then no volts. Have you tried swapping the relay as they are known to fail Embarassed
Thanks for the suggestion. I've swapped the relay and tested the socket. The ECU isn't sending voltage to throw the relay.
Will check my voltage on front height sensors and pressure sensor once the ecu is disconnected.
Thanks
Mike
10th Dec 2018 5:44 pm
MatcherMike
Member Since: 15 Sep 2012
Location: Gloucestershire
Posts: 94
Now confused!
Did some quick voltage testing. With ecu unplugged I had no voltage to the pressure sensor. But I later realise this may be as engine wasn't running.
Plugged ecu back in.
Rear height sensor (which was a real pain to get plug off!!) Measures 5v on power.
Front left measured 9v on power and signal pins initially but a few mins later measured 5v.
Front right measured 8v on all 3 pins and kept dropping over a few mins to around 5v.
I went to start engine to check pressure sensor and battery was dead. Flickering lights and dash. Battery reads 8.6v
Now 2 weeks ago I charged battery and it was 12.6v and with engine running approx 15v. I noted a couple days ago the iid reported 11.5v.
So something could be draining battery? Or battery is knackered but I don't understand strange height sensor reading.i can only assume wires are broken somewhere.
Mike
10th Dec 2018 9:07 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
Batteries will run flat in these if not used and fault finding.
I wouldn’t worry too much. Charge it.
Could be the suspension ecu.
Check the ground wire to the sensor that has 8v on all pins to ensure it isn’t open circuit
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Thanks Pete
