Left Paul Ricard circuit last night, got about an hour down road and air suspension set itself to fully up. Stopped to try and sort it,layer around with control box nothing worked, checked fuses and okay, so swapped relays over and seemed to work for a little while. Gave up and parked in services last night, set off again today and done a full days driving with no problems, but back on the original relay.
Check the lead where it plugs in Muckles. It’s exposed and a weak spot for broken wires or shorts across the plug if you lob a wet glove on it. Swap the lead with the other FH if it persists to see if that sorts it and the lead’s dodgy. Had the same happen on one of ours 
Absolutely as above swap the handset to a known good one before touching anything else.
Did have a look at the handset and seemed ok and it worked once I messed with the relays. The truck does seem to throw up electrical fault like warning that appear and go out the next day.
Try disconnecting digital counters that have a tie rod between chassis and the rear axle and see if the suspension sits in “run” position.
If the suspension resets then either one or both counters has gone buggerd.
Reconnect one at once and see if suspension works on hand set.The one that has gone down will stop suspension going to default position when reconnected as it is not transmitting its position to the control unit.
Bear in mind poking about with the ride-height sensors with the battery connected can end up needing a plug-in to sort.
What speed did it happen, if low speed I’d still fancy the handset or its wire?
It sort of happened about 3 times in quick succession, first time I wasn’t going to fast about 30 mph, I then stopped to try and sort it played around with the relays, I then could use the control box to reset the suspension. It then did it again before I pulled away and then did it at 56 mph. But the next day I did a full days driving and no problems as with the day after.
Got to say when I pulled the relays thy were bloody hot.
On mine the plug that goes into the sensor on the inside of the chassis needed tinkering with. The pins had gone back into the plug so weren’t connecting right. Open the plug casing at the back and check if the pins are level with the face. Push them in and dob some superglue on them.
Can probably rule out handset at those speeds. Might just have been some muck had got into the solenoid valve if it seems to have sorted itself. Volvo relays are known for not being great though, in terms of if it’s the actual system it’s going to be ride height sensors or their wiring supplying duff info to the ECU, knackered ECU, knackered solenoid valve or wiring to it. Beyond that there’s not really much else to it with the handset ruled out.
Thanks for the answers got a few things to look at, I think part of the problems is the trucks stands a lot so things things get damp and corrode. I’ve heard a few stories about Volvo relays not being the best. We’ve got a contact who does automotive electrics whose trying to source some better quality after market ones.
muckles:
Thanks for the answers got a few things to look at, I think part of the problems is the trucks stands a lot so things things get damp and corrode. I’ve heard a few stories about Volvo relays not being the best. We’ve got a contact who does automotive electrics whose trying to source some better quality after market ones.
i do not think it is the relays,does the small light on the hand set light up when it goes faulty,if it does not possable its a rear level sensor[6x2 has 2]4x2 has 1on the osr,disconnect one at a time till the light comes on then you know which is faulty,the hand set and the sensors use the same 5volt feed,Keith
ive had this a few times it turned out to be the level sensoron the drive axle a little box on the inside of the chassis with an arm atached to it through the chassis and a bar going to the axle…version 1 you might get away with a bit of wd40 on it and work it in version 2 it might just have to be replaced
They are the same sensor for both, just check if you have auto ride level( which levels L to R)
muckles:
Left Paul Ricard circuit last night, got about an hour down road and air suspension set itself to fully up. Stopped to try and sort it,layer around with control box nothing worked, checked fuses and okay, so swapped relays over and seemed to work for a little while. Gave up and parked in services last night, set off again today and done a full days driving with no problems, but back on the original relay.
The problem can be caused by one of the air/electric valves inside the chassis behind the cab, there are 2 one each side, one is for the drive axle and one is for the midlift a square shaped alloy valve about 6in x 6in and about 2in thick, on the older version 2’s anyway (at this time i cant remember which valve is for which axle as i have just come from the pub)
they can be repaired as they have rubber o rings inside that cut after a period of time under plastic plungers, but if you pull them to bits watch what you are doing as they are expensive to buy new iro £500+
keith 2:
muckles:
Thanks for the answers got a few things to look at, I think part of the problems is the trucks stands a lot so things things get damp and corrode. I’ve heard a few stories about Volvo relays not being the best. We’ve got a contact who does automotive electrics whose trying to source some better quality after market ones.i do not think it is the relays,does the small light on the hand set light up when it goes faulty,if it does not possable its a rear level sensor[6x2 has 2]4x2 has 1on the osr,disconnect one at a time till the light comes on then you know which is faulty,the hand set and the sensors use the same 5volt feed,Keith
do you have any fault codes in the suspension ecu…mid 150 /sid 18 or 19…believe me ,is the truck a version 2,i do theses jobs every day
Do I need to see fault codes on a laptop to check for fault codes or can I see them on the dash?
It’s a 57 plate version 2 4x2. Didn’t really notice if the lights on the hand unit were on or off, but think they were off. When I tried to lower the height the light came on as did the dash icon, but all it did was click when I pressed raise but nothing for lower or ride height.
Scroll down on the menu for self-test or diagnostic, select suspension and it will give you the fault description, code, number of instances and date of last occurance.
Cold Up North:
Scroll down on the menu for self-test or diagnostic, select suspension and it will give you the fault description, code, number of instances and date of last occurance.
Thanks for the info, I’ll give it a go tomorrow.
Just to add to Cold Up North, it should give you an error code which can be broken down into an OBD code along with a MID & PID number which are Modules and Parts numbers respectively, these can be cross referenced with parts catalogues. You just need to be careful replacing parts that are are thrown up by the lappy/diagnostics as faulty, as sometimes they can be symptomatic rather than causal, eg broken/short wires in loom or a defective ‘dumb’ part.
As for the relays, it’s not the quality of the relays that’s in question it’s the place they live, extremely hot, little ventilation & no vibration dampening.
Checked for fault codes on the dash and nothing, and its been to the workshop and they’ve found nothing. Hopefully just a glitch or we’ll have to wait until it happens again to trace the fault.