buzzer, oil light, high revs 2.1i SS

[Epiphone]

Hi Guys

Was driving through the city yesterday, which I normally don't do cos I like to keep the engine temperature down. But its pretty cold over here so thought would be ok. Hit a wave of read lights so was ticking over for some time and revving up and down going through 1,2,3 gears mostly. Then got the buzzer of doom. Pulled over stopped, restarted the engine and it didn't come back on. Then drove a few metres more (probably going above the 2250 rpm) and it came on again. Parked up for a 20-30 mins and then came back, but a little bit of oil in (even though the level was good) and went straight onto the ring road so to get some constant driving and not stop/start stuff and made it home, driving 60kmh etc without issue.

Drove out today and buzzer came on again when putting some revs on. Was fine at tick over and driving around my underground garage. Let it warm up at tick over for 5-10 mins and then was able to driving 4km without the buzzer sounding.

Parked it up for 1.5 hours and then when came out, buzzer came on again when accelerating, fine at tick over. Then I definitely noticed that if I kept it under 2000rpm then the buzzer didn't sound. But as it warmed up this threshold raised and then 1 time I dropped the revs down and the buzzer stopped. I then tested it again and was also able to activate the buzzer by going 3-4000 revs.

It has been very cold over here and it seems when it warms up its ok. But then the first time it happened, while driving through the city, it was running at hot temperature. So by reading the wiki, it seems its the high revs/low pressure sensor activating the buzzer, cos its fine at tick over.

What should be my next steps?

[toomanytoys]

1st off.. if you dare not do city driving coz your worried it will get to hot. you really ought to get the bottom of why its getting hot... hot weather sittig in trafic shouldnt cause any vehicle an issue..

2nd... oil buzzer will come on if pressure is below 2 bar above 2000 rpm.. (or something like that its been a while since I had to look it up)
But... the pressure swich could have gone faulty.. so either get a new good quality one.. (sits next to water pump pulley) and see.. or better still get the oil pressure checked ..

also has anyone been messing about in the engine bay just before it started??? the wire could have been pulled off/damaged.. as it needs to see an earth to not buzz...

[Epiphone]

In this weather I have no opportunity to work on the Bus. So Will definitely give it a rest now until Spring time.

It probably gets too warm due to an airlock, after I dumped the coolant on the floor last summer. Ive still not found the nack for bleeding the system. But I always been OK on the motorways. I want to change the coolant anyway, as im currently only protected to -15.

Ordered a pressure sender and will fit this and the gauge when the weather warms up too. As well as new sensors.

Can anyone recommend an on-line retailer for the hose and T-Piece/s?

[Epiphone]

This is all I can see of the High/Low pressure switch. The heat shield obscures it from that back.

By removing the cam belt I can get access from above, but the switch is quite long and therefore my 24 socket is too short. Can I get a longer 24 socket? The ones used for the spark plugs would work, but in 24.

Is the only way with a spanner from the side, but I find it hard to believe I can fit a 24 spanner in that space and still have room to move it more than 2 inches?

[ghost123uk]

This is all I can see of the High/Low pressure switch. The heat shield obscures it from that back.

You can barely see it at all, but you can feel it and get a spanner onto it. I did ours a couple of years ago. it was awkward to get to but not impossible. ( I used a combination of open ended and ring spanner, not a socket).

By removing the cam belt I can get access from above,

I seem to remember I too took off the fan belt (note, FAN belt not CAM belt, just a language thing I guess ) to help get at the high pressure sender. I (we) hope you ordered a good quality one (from a reputable supplier) as there are some poor quality ones around (that can not only fail to "sense" pressure correctly, but can leak oil out !)

p.s. What is the problem bleeding it ?
Here is a "how to" = https://club8090.co.uk/wiki/Co ... ing_system" onclick="window.open(this.href);return false;

Years ago, when I had to flush oil out of my cooling system, I had to flush SO MANY TIMES that I got the bleeding thing off to a fine art taking only 10 mins per time, often randomly at the side of the road

[Epiphone]

ok will go and buy a 24 open and ring spanner at the next opportunity.

I didn't want to call it FAN belt, cos there isn't a fan at the back is there.

[ghost123uk]

I didn't want to call it FAN belt, cos there isn't a fan at the back is there.

Very good point = never actually considered that before !

[Epiphone]

so while I was fiddling around with the high/low pressure switch I thought I would take a look at the cable and noticed that it was in very bad condition/melted near the switch end. Ive replaced it and went for a drive today, and it was fine, even in slightly warm weather.

Just goes to show, check the little things first

Once I've ordered the high pressure hose, I will fit the pressure gauge anyway. Planned for my easter holiday

[toomanytoys]

I did mention the wiring

[Epiphone]

Hi, ok issue is back again. It did disappear as mentioned. But then I drove it in the rain last week and the buzzer came on for a 2nd then stopped. I was only driving a short distance.

I drove it to work today to test it, a 30 min drive and the buzzer was coming on everytime I was going over the 2200 rpm limit. I tried disconnecting the cable from the high rev/low pressure switch but it was still coming on. I tried grounding the wire also, still came on. It comes on when driving along, if im stationary and rev it up, it doesnt come on

So would u say its my DOPWS chip etc?

How do you turn the buzzer off again?

Is this statement for Diesels only?

The flashing oil pressure light is operated alone by the high-low pressure switch and hence at engine speeds of over 2000~2250 rpm.
The flashing oil pressure light and 'buzzer of doom' are operated by the low-low pressure switch, hence at lower engine speeds.

T25 SS - 1989 is buzzer and light at high revs. Not sure about low revs, never experienced anything yet

[Epiphone]

from the wiki

If you earth the wiring and the buzzer still goes, check for break in circuit somewhere (14 pin plug under dash cowl one suspect.)

so this is definitive proof that there is a break in the circuit as grounding would stop the buzzer?!

Should I be running a wire from the sensor to the dash to test?

[ghost123uk]

from the wiki
If you earth the wiring and the buzzer still goes, check for break in circuit somewhere (14 pin plug under dash cowl one suspect.)

so this is definitive proof that there is a break in the circuit as grounding would stop the buzzer?!

Yes

Should I be running a wire from the sensor to the dash to test?

You could, but with very basic test meter knowledge, using one would be an easier way to check continuity. Like = earth the engine end and the use the meter to check for full continuity to earth at the dash end. If non, then a break, if good then either a faulty sender (new I know but not impossible at all) or a fault in the dash.

Try temporarily earthing the wire at the dashboard end, that should stop the buzzer. iirc it does not need to be re-set, but should turn off straight away, but I would like someone to confirm that, it is a while now since I worked on DOPWS.

As you say it only occurs when driving, it is very unlikely to be an chip fault, more like a mechanical one, ie bad connection.

[Epiphone]

photo.JPG

Is this known as the T14 - 14 pin connection dash panel insert? Im learning how to read this diagram then. According to the diagram below its the connection coming from the Pressure switch into E15 - connector on the relay plate - then coming out at B12 connector on the relay plate as a yellow wire and connecting into the back of the instrument panel at T14/12 (wire 12). So its the yellow one above?

Ive got the Haynes wiring diagram - Typical Dash panel insert, optical and acoustic oil pressure warning

wiring.JPG

Hacksawbob The cuircuit board under the dash pod can get corroded (sometimes badly from windscreen corrosion badly fitting seal) pry off dash pod and trace the white plastic block that feeds it, disconect it and buff up the copper contacts with a green scouring pad can also fix disco lighting effects on the dash warning lights.

[Epiphone]

Hi, OK got it working again.

So after establishing that I couldn't even ground the circuit out. I replaced another cable, from the connector (double connector with the low rev-low pressure sensor is on) to the junction box in the engine room. I found that the resistance on this cable was very high.

I then put the new cable to earth and it worked, no buzzer.

Then I put the new cable to the high rev-low pressure switch and it worked no buzzer.

I also tested, disconnecting the cable, then driving down the road over 2250 revs and the buzzer sounded, and then reconnecting and then once I pressed the accelerator buzzer stopped.

So I assume that when I had the first occurrence of this issue and I replaced only part of the cable in the engine room, this allowed the total resistance to be just enough to ground out.

Then some time later, the rest of the old cable deteriorated enough so that it couldn't be grounded out again.

So I should anticipate the deterioration of the cable in the rest of the Harness and run a cable up to replace this?
Or was this just to being more exposed to the elements in the engine room?

Thanks for the help and my beginners lessons in testing for resistance on a cable

[ghost123uk]

Sounds like a good result (and congrats on figuring out the Heynes diagrams)

Should anticipate the deterioration of the cable in the rest of the Harness and run a cable up to replace this?
Or was this just to being more exposed to the elements in the engine room?

I think you are likely correct, it was a result of heat and general exposure in the engine bay.
I would expect the rest of the cable is fine.