VDO oil pressure sender

[HXsman]

Hi All, I have tried two senders now both without luck the gauge barely makes it to the red zone. HX GTS Gauges - WB Blue 254 ? _ have grounded the wire and the gauge works fine.

Any thoughts on the right sender ? - I bought one this week from Kingswood country but it didn't work.

Appreciate your help

[panoz78]

If you have replaced the sender and checked your gauge which you have
the next thing is to fit a mechanical gauge and see just how much oil pressure is there.
The factory gauge tend to be a bit slow on their reaction time compared to a mechanical ..
You should have at least 20psi hot at idle.
Mechanical gauge is good insurance..

[HXsman]

Hi All,

I am now onto my fourth sender and at $80 a pop its getting frustrating. I am now using 360.005 and the needle barely moves out of the red zone (cold) and once warm and idle pretty much goes back to nothing reading at all.

When I ground the wire the needle goes full range.

Is there any danger of damaging anything if I run a test wire from the sender to the back of the gauge (to rule out a wiring issue) ?

Appreciate your thoughts


Dean

[Dr Terry]

Go to Jaycar & purchase 3 resistors, they are very cheap, around $1 should cover all 3.

The ones you need are 75 ohms, 25 ohms & 10 ohms.

Substitue the resistors, one at a time in place of the sender & switch on the ignition. In other words disconnect the sensor & earth the wire thru the resistor.

I would fit the 25 ohm one first, let the gauge warm up (5 mins is plenty) & it should read half scale. Now try the other 2. The 10 ohm one should read full scale & the 75 ohm should make it read zero.

If the gauge does not read correctly, either gauge needs repair or recalibration or the volt reg (in the gauge case) is crook. Just take the gauge unit to a pro.

It's highly unlikely that you've bought 4 faulty senders.360.005 is the correct sender for HJ to WB commercial.

In my experience oil pressure at warm idle is usually in the red zone. As you raise the revs the gauge will move up, but it is slow.

Dr Terry

P.S. It's not a good idea to ground the sender wire directly to earth for any more than a second or 2, this can damage the gauge. This is why I use the resistor.

[HXsman]

Thanks Terry,

I was kind of hoping you would respond, really appreciate your thoughts. Ill give it a go this weekend and see how I go.

Is the voltage regulator in the four gauge cluster or elsewhere in the dash?

Cheers


Dean

[Dr Terry]

Is the voltage regulator in the four gauge cluster or elsewhere in the dash?

It's inside the 4-gauge cluster.

Dr Terry

[HXsman]

So I finally had a chance to do the resistor test with mixed results. (see below). Appreciate your thoughts. Included the resistors in case I had them wrong

RESISTORS.jpg75-OHM.jpg10-OHM.jpg25OHM.jpg

[damienengland]

So I finally had a chance to do the resistor test with mixed results. (see below). Appreciate your thoughts. Included the resistors in case I had them wrong

RESISTORS.jpg75-OHM.jpg10-OHM.jpg25OHM.jpg

HXsman, the resistance values quoted, don't line up with the expected results on your gauge cluster. The 10 ohm resistor should have given you full scale deflection of the needle. Can you confirm the pics?

[HXsman]

Hey Damian, Ill run them again in the morning, thanks for looking

[damienengland]

If it gets a bit confusing, you can always break the system down to its core components and do process of elimination. In bigger terms, you should have 1) Sensor, 2) Wiring, 3) Gauge cluster and two of these can be tested fast. If you transpose the resistor concept, you could measure resistance instead of introducing it. Have a look at the following document link. If you know the possible resistance range for bad or good oil pressure, then disconnect the sensor wire and connect a multimeter to the sensor to watch the resistance change when you run the engine. If 73 ohms is lowest gauge position and 10 ohms is full scale, then you can judge the values you read on the multimeter against the running conditions. For example, a cold engine will generally deflect the needle a long way up the scale before it gets hot, so you might expect to see much lower ohms on the multimeter at this stage. If it looks good, move the multimeter to the wire as it connects to the gauge cluster and repeat. if it looks good, then the gauge should be the culprit.

Link here: http://www.bolec.com.au/105001nocap-r4c.pdf