Engine/Transmission (1994 - 1998) Stupid oil pressure gauge

[TLarsen]

It's my understanding that (on my '98 12V) if the engine oil pressure drops below ~30psi, the computer just knocks the gauge down to 0psi. Is that true?

This started the DAY I had the GSK installed. After the truck has been driven about 20 miles and reached about a 160 degree operating temperature, when I stop with the truck idling in gear the oil pressure gauge will instantly drop to zero psi. But if I bump the engine rpm up about 100-150 rpm with the throttle pedal, the pressure instantly jumps to a "normal" 30-40psi. Normal engine idle speed when warmed up, in gear, with the AC on is about 800 rpm. And yes, the engine oil level is correct.

Oddly enough, the few extended trips I have taken the truck on since this started, it seems that once the engine is fully warmed, this doesn't happen. Its almost always happens about 20-30 minutes after initial start up.

I have been around enough engines that have lost oil pressure that I am sure my Cummins is not actually losing all oil pressure, but below some 30psi threshold it seems like the computer or the gauge just drops the gauge indicator to zero and dings the check gauges light.

This is quite irritating, and during the 35k miles I put on the truck before the GSK install it never did this once. Since the GSK install, I have switched the truck from Delo 400 15W40/Wix filter to synthetic Rotella T 5W40/Fleetgaurd filter at a normal oil change, it still acts the same.

 

[MFalkinham]

My '98 was doing the same thing, including the check gauges warning light coming on with an annoying chime at every stop sign. I changed the oil pressure gauge sender which didn't help, so then I paid the dealer to perform the following TSB. It basically turns your oil pressure gauge into an idiot light, but I also have an aftermarket OP gauge installed for confirmation of good pressure.

TSB 08-22-99

 

[GAmes]

A few months ago I managed to break my sending unit while replacing the pwr steer pump. For the 535k miles I had driven it, the gauge always stayed just above 40, warm, cold, idle or at speed. I got a new one from Car Quest, and now I have a functioning gauge, above 40 when cold and below 40 when warm and at idle. Not sure if it fits a 98. Part # EC PS-233

 

[TLarsen]

I paid the dealer to perform the following TSB. It basically turns your oil pressure gauge into an idiot light



TSB 08-22-99

That looks like the exact issue. But what do you mean it turns it "basically turns your oil pressure gauge into an idiot light"? Do you mean it's either on or off after the flash?

 

[MFalkinham]

After this flash, the gauge functions the same as an idiot light. If there is oil pressure, it shows a reading somewhere within the normal range. If there is no pressure, it will show zero. The actual needle position becomes meaningless when compared to my aftermarket oil pressure gauge. It was still worth doing to get rid of the chime and warning light.

 

[JBeasley]

I have a buddy with a similar problem on a 94. His guage started bouncing around a couple weeks ago so he put a new sender in it. That fixed it until today he called me and said it started doing it again. Is it something else or does he have my kind of luck and just got a bad sending unit?

 

[roosp]

My 96 model started this about six months, at idle things appear normal but when I accelerate it drops to "0". I also have a mechanical gauge installed, but would like to the solve problem. I have about 290,000 miles on the truck, thinking maybe something electrical going on? Oo.

 

[Missouri Mule]

My guage one night on the highway started reading under 40 psi it then dropped to zero bounced back up above zero sevaeral times I was doing 75 mph as I slowed to get off at my exit it went back to under 40 psi at 55 it was reading over 40 psi.

I had new oil pressure sending unit put on and all is well again.



If it is not your sending unit it could be the guage.

 

[BTanzini]

Hey guys I checked the wiring diagram on my 96 and the sending unit go's directly to the instrument panel for pressure and idiot light not through the computor. F. Y. I.

 

[JBeasley]

I just found out that my buddy replaced his with an O'reillys sender instead of a Dodge one. I'm sure he probably got a bad one. I ordered 2 from Dodge. Mine acted a little funny a few months ago but it only done it once. I'm going to go ahead and replace the sender. $31 apiece from my local dealer.

 

[WPeschel]

It's my understanding that (on my '98 12V) if the engine oil pressure drops below ~30psi, the computer just knocks the gauge down to 0psi. Is that true?



This started the DAY I had the GSK installed. After the truck has been driven about 20 miles and reached about a 160 degree operating temperature, when I stop with the truck idling in gear the oil pressure gauge will instantly drop to zero psi. But if I bump the engine rpm up about 100-150 rpm with the throttle pedal, the pressure instantly jumps to a "normal" 30-40psi. Normal engine idle speed when warmed up, in gear, with the AC on is about 800 rpm. And yes, the engine oil level is correct.



Oddly enough, the few extended trips I have taken the truck on since this started, it seems that once the engine is fully warmed, this doesn't happen. Its almost always happens about 20-30 minutes after initial start up.



I have been around enough engines that have lost oil pressure that I am sure my Cummins is not actually losing all oil pressure, but below some 30psi threshold it seems like the computer or the gauge just drops the gauge indicator to zero and dings the check gauges light.



This is quite irritating, and during the 35k miles I put on the truck before the GSK install it never did this once. Since the GSK install, I have switched the truck from Delo 400 15W40/Wix filter to synthetic Rotella T 5W40/Fleetgaurd filter at a normal oil change, it still acts the same.

Mine does just as what yours is doing... I installed the new sender today from orielly and it helped it only goes to 0 when I lug it to 500rpms taking off in 2nd... .

 

[TLarsen]

Mine does just as what yours is doing... I installed the new sender today from orielly and it helped it only goes to 0 when I lug it to 500rpms taking off in 2nd... .

I am planning on putting a new sender in it, it's good to hear that it might take care of the irritation, especially since I never lug the engine that low with the auto trans. Thanks.

 

[TLarsen]

Hey guys I checked the wiring diagram on my 96 and the sending unit go's directly to the instrument panel for pressure and idiot light not through the computor. F. Y. I.

I was thinking about this, the computer has to have something to do with it. The TSB posted above indicates that they can flash the computer to "fix" the problem.

 

[Missouri Mule]

But is the TSB for 12 valve engines or 24 valve engines? The TSB came out in 99 for 98 trucks(it looks like for diesels and gassers). The TDR and few other Dodge/Cummins web sites desinate the 24 valve as 98. 5s but I bet Dodge doesn't.

 

[Lightman]

The 98 12valve is the only year 12valve that has the oil pressure sending unit go to the computer then the gauge same thing gos for the coolant temp sensor.

 

[Stark_Ent9802]

wow , i thought my truck was the only one that did this. Mine drops to 0 sometimes (not every time ) at a stop when the truck is warm. This is especially annoying when snowplowing. I was assuming it was the sending unit. I also Had a mechanical oil pressure gauge to confirm i still had pressure even though the dash gauge read 0.

So to replace the sender or perform the TSB... hmmmmm

 

[HerbW]

Lightman is right on!

Lightman is right on the money! It is only the 1998 12 valvers with this trouble. I have this trouble and am so tired of dings and zero pressure if I let my truck drop to normal idle, I'm gonna go for the TSB to fix. Mine is worst with AC on sitting at a light in hot weather. If your truck isn't a '98 don't assume it's a programmers fix. IT could cost some bucks. I heard their is a way to add a resister in parrallel to the sender to fool the "brain" and prevent this ding zero pressure crap. Any ideas about this? My local Dodge ******* repair shop didn't know of this TSB. Scary!:{:{

 

[Stark_Ent9802]

Hey,

I bumped my idle up alittle and have not had the problem since. (Thank god) Idle is now at like 800 at idle. !!!

Some eles told me to before you replace the sender try cleaning the connector with some cleaner

 

[HerbW]

I have solved this if I put my truck in neutral and rev it up a bit. I'll try that. I'll have to reread on how and where the idle is set at. It's pretty low now. It get real bad when I back my truck up. It makes me crazy to ding over and over again. Thanks. Herb

 

[Stark_Ent9802]

Trust me man i was there! I hated it! Truck was stalling out in reverse with the a/c on . My Buddy did the idle adjustment. sorry i could not describe to you how to do it. But im sure if you ask someone on here would describe it.