Oil Pressure issue on 350 Cummins ISC

[oregondarrell]

Engine oil pressure on our 350 Cummins ISC was always 75 lbs pressure.
On trip to Oregon - My oil pressure gauge read - with engine "off" 30 PSI.
When engine running it rose to 125 PSI.

Asked Cummins in Coberg to check it out during May oil change and road check.
Cummins replaced the oil pressue sender that Monaco installs adjacent to oil filter.
My oil pressure guage is now fully deflected to right - no movement at all - pegged to far right of gauge.
Cummins told me they must have installed wrong OHM sender but did not know what sender was needed. 

I have researched internet and found that I needed a 0-100 PSI sender with 33 -240 ohms.
I purchased a Datcon pressure sender from Amazon with those exact spec's.

Nothing - The gauge is still pegged to full deflection and no movement with or without the wire connected.

Do you think Cummins damaged my gauge with an incorrect sender or something else ?

Any help appreciated

[BradHend]

May not hurt to be doing a fairly thorough inspection of the wiring leading up to and behind the senders connection point.  
Possible some consequential damage happened in the replacement process. 

Are you able to get your original sender that Cummins replaced back? 

Edited July 15, 2023 by BradHend

[timaz996]

My oil pressure gauge has always been pegged and very rarely will show the accurate pressure for less than a minute. All of my gauges have sucked since I’ve owned this coach and that’s why I went to a scangauge D.

[oregondarrell]

35 minutes ago, BradHend said:

May not hurt to be doing a fairly thorough inspection of the wiring leading up to and behind the senders connection point.  
Possible some consequential damage happened in the replacement process. 

Are you able to get your original sender that Cummins replaced bac

No - They tossed it. I returned to see if they figured out how to fix it several days later, but they had no idea what was wrong.

[jacwjames]

Not sure if the Safari's had the same setup as Monaco did on my Windsor.

There are 2 oil pressure sensors, one for the dash gauge and one that provides a signal for the ECM.  The correct oil pressure sensor for the gauges on my coach is https://www.amazon.com/VDO-360004-150-Pressure-Sender/dp/B000NBE6GK

When I first got my coach in 2008 the oil pressure gauge was pegged.  Once I got it home I took it to Cummins for a complete service/inspection.  Asked them to check the oil pressure issue.  They said the sender was installed in the wrong place, they fixed it and the gauge now does move but it reads high.

 

I  don't rely on my dash gauges very much, I display the important info on my Silverleaf display.

[OhReally]

Can't speak to whether Cummins damaged your gauge but if they didn't check the gauge function after installing the new sensor then they definitely owe you a refund!

As for the 2003 ISC 350hp sensor, it should look like what Jim suggested but it probably has two terminals, not one. The connections to the sensor are marked G and WK on the sensor. Amazon does have these or Jegs or O'Reilly. If you have the two terminal one, it is p/n 9832. Be careful not to swap the G and WK wires. If you do it won't work. That may be your problem with what Cummins installed.

[oregondarrell]

The oil pressure sender I purchased has two terminals;

WR - Warning Switch  ( Narrow blade)

S - Signal Output   ( Wide Blade)

I attached wire to S - Signal Output

I did not try WR as I assumed it was for an Idiot Light

[OhReally]

Darrell, I have never seen that marking before but I feel fairly confident your WR is my WK and your S is my G. The curious thing about this device is that it is both a variable sensor and a switch.

I am fairly confident that the switch part provides a go/no go signal to the ECM as well as to an idiot light. When the idiot light is turned on by the WR or WK it also sends a signal to the ECM and you get an engine shut down light and the ECM can command limp mode.

If the above is actually correct and you have two wires for the sensor, you do need to connect both terminals in the correct arrangement.

BTW I recently replaced my sensor with the p/n 9832 from O'Reilly's and my ISC is happy again. Cummins said they had no knowledge of the two terminal sensor for this engine ESN so it must have been a Monaco/Holiday Rambler installation, even though it serves the ECM. Cummins does list several similar sensors but denies their application for the ISC. Go figure....

[jacwjames]

The parts page I have listed two different senders, based on when coach was built.  The second sender is this

https://www.partdeal.com/vdo-80-psi-standard-ground-pressure-sender-6-24v-with-7-psi-warning-contact-point-and-1-8-27-nptf-thread-bulk-360-009b.html

 

[dholden_us]

Sometimes analog gauges stick when pegged

  Have you tried tapping the face to see if it's stuck? 

 

 

[oregondarrell]

I'm starting to think I might have a Ground issue.

The paperwork that came with Datcon pressure sender says 

"ground is through case - Make sure it's connected"

There is only one wire on my RV which I assume runs to dash gauge.

Three questions

1) Should I attach a ground to Sending unit  ?   Maybe with a hose clamp as there is no lug for ground.

2) With Datcon sender that I purchased  -  which blade connector should I connect to the single wire to gauge ?    WR - (Warning switch )  or   S - (Signal output)  

3) The VDO sender that Cummins installed and deflects fully to right,  also has two connection lugs  - (  G ) and (WK)    Is the G for Ground ?

 

Very confusing

20 minutes ago, dholden_us said:

Sometimes analog gauges stick when pegged

  Have you tried tapping the face to see if it's stuck? 

 

 

Tapped several times - Didn't work

[dl_racing427]

Start troubleshooting by turning on the ignition, without starting the engine, and note the gauge position.
Then disconnect the wire from the sensor and see if the gauge moves.

Most gauges will go to 0 when the wire is disconnected, and max when the wire is shorted to ground. (Do that only momentarily).

If that checks out, the gauge and wiring is ok, and you just need to find the correct sender for your gauge.
See if the gauge has a p/n and try to look up the sender from that.

[OhReally]

1 hour ago, oregondarrell said:

I'm starting to think I might have a Ground issue.

The paperwork that came with Datcon pressure sender says 

"ground is through case - Make sure it's connected"

There is only one wire on my RV which I assume runs to dash gauge.

Three questions

1) Should I attach a ground to Sending unit  ?   Maybe with a hose clamp as there is no lug for ground.

2) With Datcon sender that I purchased  -  which blade connector should I connect to the single wire to gauge ?    WR - (Warning switch )  or   S - (Signal output)  

3) The VDO sender that Cummins installed and deflects fully to right,  also has two connection lugs  - (  G ) and (WK)    Is the G for Ground ?

 

Very confusing

Tapped several times - Didn't work

Yes, G is for Ground but do not connect it to ground. The ground comes from the sending unit when oil pressure is available. Do not add another ground with a hose clamp. That won't hurt or help anything.

As DavidL said (with my additions), 1- disconnect any wires at the sending unit, 2- check the gauge reading, 3- turn on the ignition (,do not start engine), 4- check the gauge, 5- reconnect the wire(s) to the sensor, 6- check the gauge, 7- turn on the ignition (,do not start engine), 8- check the gauge.

If the gauge now deflects all the way to full in step 2, 4, 6 or 8, you have a problem and we need to know the gauge reading in each step (2,4,6,8).

After knowing the gauge reading for each step we should have solid information to continue troubleshooting your problem.

[oregondarrell]

With Datcon sending unit installed

Wire not connected - ignition off  - full right deflection

Wire not connected - ignition on  - Full right deflection

Wire on S connection - ignition off  - full right deflection

Wire on S connection - ignition on  - full right deflection

Wire on WR connection - ignition off - full right deflection

Wire on WR connection - ignition on  - full right deflection

 

Should I try same with the VDO sending that Cummins had installed ?

[oregondarrell]

I also did as  dl racing 427 suggested ;

I shorted wire to RV frame with ignition both off and on and still had full scale deflection of gauge.

 

[OhReally]

Sounds like gauge is toast. May have been toast before Cummins replacement. One final check would be to use an ohmmeter.

1- Disconnect wires at sensor

2- set meter to resistance (ohmmeter)

3- connect one ohmmeter lead to S or G on sensor

4- connect 2nd ohmmeter lead to engine ground

5- read ohmmeter results

6- start engine and read results again

Post results from 5 and 6.

[dl_racing427]

On 7/16/2023 at 1:41 PM, oregondarrell said:

With Datcon sending unit installed

Wire not connected - ignition off  - full right deflection

Wire not connected - ignition on  - Full right deflection

Wire on S connection - ignition off  - full right deflection

Wire on S connection - ignition on  - full right deflection

Wire on WR connection - ignition off - full right deflection

Wire on WR connection - ignition on  - full right deflection

 

Should I try same with the VDO sending that Cummins had installed ?

Sounds like the gauge itself has failed.
If it were returning to 0 when the ignition is off, it could be a shorted wire between the sender and gauge, but most gauges mormally return to 0 when power is off.

That said, some gauges have floating movements, which don't necessarily return to 0.  In that case, it should go to 0 when power is on and the sender is disconnected.

I still think it's most likely a bad gauge..

[oregondarrell]

dl_racing427,

 Thanks ,

That's what I figured after the results I posted.

I ordered a new gauge from AutoMeter that is similar and comes with sender.

Hopefully that will solve my issue.

Thanks to all who responded with ideas and suggestions.

[dl_racing427]

On 7/17/2023 at 7:18 PM, oregondarrell said:

dl_racing427,

 Thanks ,

That's what I figured after the results I posted.

I ordered a new gauge from AutoMeter that is similar and comes with sender.

Hopefully that will solve my issue.

Thanks to all who responded with ideas and suggestions.

Good choice.
I've used Auto-Meter gauges in my race cars for years.  They're tough and accurate.