[jr90]

I'm trying to figure out how to make the gauges work in my 90 d150 with 99 5.9.  Does anyone know if the resistance is the same for oil pressure and temp sender?  Does the computer need the oil pressure reading to run correctly? I know it doesn't have the reading in obd2 functions so want sure if it was necessary.  Thinking I'm going to put in a 93 fuel pump for fuel gauge or get a 90-0 sending unit and use a dakota digital signal converter for speedo.  Any suggestion on  temp, oil pressure and fuel?  I'm pretty sure I have no other option for speedo.

 

[dodge82273]

you should get a '99 factory service manual's wireing diagrame and a '90's . I only go to '93 mag ,  If the '90 had the tall plastic oil switch , it will screw into the hole of a mag motor, same for the temp sender and temp sensor . the trans/transfer may have the spot for a sender , use the '90 screwed in there ... and the 90 dash ?

 

[jr90]

I've tried tracing the wires and tieing into them and got oil pressure gauge to move but it was showing low, temp never moved.  That's why I asked about senders.  I dont want to replace the senders and have  the computer into limp mode.

 

[dodge82273]

at this I restate you need '99 book and a 90 book , or look up and compare replacement part numbers , if the replacement part # is the same ........ 

 

[jr90]

I don't think the manuals are going to help me.  I got the temp gauge to move but it's not reading correctly  either so the senders must be different.  I'm wondering  if there is a way to convert the signal or if I can put a t into the ports and use both senders.  Hopefully  somebody has some experience they can share.

 

[t84w150]

Take a look at a 96 engine. There are 2 temp sensors. one for the gage and one for the PCM. I think the casting is the same for a 99. should be a nice flat spot next to the thermostat housing to drill and tap for another sensor. For the oil pressure I used the magnum sensor. works fine. I swapped in a cluster with electric speedo from a 93. earlier clusters may be different. The temp sensor should work on any cluster. just use the one for that cluster.

are you 2wd or 4wd?

 

[jr90]

From what I read all 99s have one temp sender but I can drill and tap a new one.  Honestly it didn't  occur to me to try that for some reason.  Since the oil pressure  didn't read correct it may be different for an la engine, I may just try to put a splitter in that and run both senders but I'll put in the 90 one first to test.  Mine is 2wd.

 

[dodge82273]

you want temp sensors and senders to be immersed in the coolent , a tee there may not work well , But a tee for the oil pressure will work fine . 

 

[Mechanized]

X2 on what was said with the coolant sender. It needs to have coolant rushing passed it. If you place it into a t it will not be accurate. I've played this game. Oil pressure is fine in a t set up.

 

[stftruck]

I don't think the oil pressure sensor sends a single to the ECM does it?

 

[Mechanized]

It does via a gray and orange wire it appears. As to what function that provides I have no clue. It could be as simple as turning on the light on the dash and moving the gauge needle. It could be as complicated as to use that in put to enable other features. I have included a diagram below

 

[pc1p]

I'm trying to figure out how to make the gauges work in my 90 d150 with 99 5.9. Does anyone know if the resistance is the same for oil pressure and temp sender? Does the computer need the oil pressure reading to run correctly? I know it doesn't have the reading in obd2 functions so want sure if it was necessary. Thinking I'm going to put in a 93 fuel pump for fuel gauge or get a 90-0 sending unit and use a dakota digital signal converter for speedo. Any suggestion on temp, oil pressure and fuel? I'm pretty sure I have no other option for speedo.

I believe the resistance is the same, but recall seeing something in the later-year FSM's that the oil pressure gauge goes to a BCM/Bus rather than directly to the gauge. I'm not 100% sure since it was a while ago when I was doing research for my Magnum swap. However, I do know that a PS204 oil switch - the one from your '90 will thread into the '99 5.9L without issue and you could use the factory connector as well. However, not that on the '90 TBI engines, the oil pressure connector goes through the large, square 50-way connector on the right side of the engine. You'll need to cut it off there and solder/connect back to the main harness. On all the pinouts that I've seen for the OBD-II ECM's, I have never seen a oil pressure switch input and do not believe it has any influence on engine operation.

For the fuel pump, you'll need a '91+ tank to accommodate the different style fuel sender. You'll also need to find a flat-style electrical connector for the later-style module. These modules are a return-style sending unit, though your 96+ engine will have a single-feed, returnless style rail. You can find an earlier style fuel rail, but what I'm finding out at the moment is that it's much easier to use a 99-01 Grand Cherokee style fuel filter w/built-in pressure regulator.

For engine temp, the 98+ Magnum manifolds do NOT have a provision for a coolant temp switch for the gauge. The later Magnums use data off the coolant temp sensor via the ECM and then transmits that to the gauge pod/BCM. You can drill and tap (I believe 1/8" NPT) and install a 90 Dodge V8 temp switch to operate your gauge. Alternatively, you can use one of those radiator hose adapters that have the 1/8" NPT provision to run a factory style coolant temp switch.

For the VSS/speedo sender, as you know you'll need a converter to convert the TBI, 2-wire 4k pulse per mile (ppm) sine-wave signal to a 8k PPM square-wave. There are many options to do this, but remember it's almost always best to install the module INSIDE the cab. However, if you're using a '98 transmission, be aware that this was a transition year. I believe Dodge transitioned away from a trans/t-case speed sensor and went to a speed sensor/combo on the axle. I don't have the 98+ FSM to reference but I do recall seeing something weird about the VSS as well (all these reasons are why I went with a 96-97 OBD-II setup on my Magnum swap).

 

[Mechanized]

If you you look at pin 23 of the pcm of the diagram I posted earlier it clearly shows input. Here is the other half of the diagram. Notice the gry/org to the pressure sender

 

[jr90]

Thanks for the information, I have a 92 or 93 tank not sure which and a pump from a later year but not certain which.  I was thinking of just getting a universal sender and installing  it into the tank.  I think I'm going to stick with the splitter for the oil pressure and drill and tap for the temp sender.  I'm going to try the Dakota digital converter.  everything I'm running is from a 99 since a had a wrecked pickup to pull from, I installed the newer speed sensor in the 90 axle and it cleared the p0500 code so it should give the converter the signal it needs.

 

[SuperBurban]

Another possibility, is the adapters sold to mount the sender in the radiator hose. I have seen them on ebay, amazon. I bet many other places have them also. Just need to get the right size. The extra screw is to run a ground wire.

 

[jr90]

Seems like the oil pressure is working but didn't have time to get to temp. Are there any recommendations for signal converters for speed other than dakota digital?  The trans uses the tailhousing speed sensor to shift correct? or does that one serve another purpose?

 

[thestigmachI]

It does via a gray and orange wire it appears. As to what function that provides I have no clue. It could be as simple as turning on the light on the dash and moving the gauge needle. It could be as complicated as to use that in put to enable other features. I have included a diagram below

im working on the same issue with mine trying to get working gauges. which year are the diagrams you posted for?

 

[Mechanized]

im working on the same issue with mine trying to get working gauges. which year are the diagrams you posted for?

It was for a 99. All the gauge diagrams are the same with the exception of the 6cyl Cummins.

 

[jr90]

I did go with the t for oil pressure and drilled and tapped the manifold for the temp sender.  Both are working now, just need to get the signal converter and find a fuel sending unit which I haven't been able to find yet.

 

[Mechanized]

99 is still showing mounted on transfer transfer case. The signal is then sent to the data bus and interpreted by the gauge cluster.