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So just when i thought i had most of the stuff in my car up an running my oil pressure gauge seems to take a crap on me. I noticed it while driving down to school. The gauge is constantly on 0-15psi and never rises above it. The normal place it would sit at is around 30-45psi. Im pretty sure its the sending unit, but i did remove my gauge cluster recently.
Would a failure in the sending unit cause a check engine light to come on? I installed the speedo override switch and when i flip that on it throws the SES light but sometimes while im driving the check engine light will come on randomly but when i throw my speedo switch it erases it but it will occasionally come back on.
Im at school now and cant really get to work on it so is there anyway to tell what my oil pressure really is? Or what are some common things i should look for with low oil pressure? Also does anyone know how much a scanner would cost that reads codes? Like i said im at school and i dont get out to drive much. Any help is greatly appreciated.
The computer doesn't know and doesn't care at any time what the oil pressure is, so it isn't turning the SES light on. The first thing to check when you have low oil pressure is the oil pressure sending unit.
A code reader costs less than 4 cents, and is available in boxes of 100 at Staples.
Would a failure in the sending unit cause a check engine light to come on?
No.
Quote:
is there anyway to tell what my oil pressure really is?
Sure; replace the sending unit, or get an outboard gauge and hook it up too, discover the sending unit is bad, and THEN change it out. Either way, change the sending unit. Personally, I can't see where adding another gauge really saves much time or money, over just changing out the sending unit, but that's just me; I'm pretty stupid sometimes. (well, all the time, really....).
Quote:
does anyone know how much a scanner would cost that reads codes?
Anywhere from about $80 to several $1000. Won't tell you a thing about oil pressure though.
Just get a sending unit and change it out. Pretty normalish kind of thing to have to do on an old car. I've been through a few myself.
Can't see how being at school is really going to change the picture too much, or get the sending unit to work right or something, or much else; but I could be wrong about that. Not germane to the matter at hand. Like I tell my college-age children (and they are tired of hearing it!!), sometimes you just gotta do what you gotta do, even if it seems a bit tough.
__________________ Numquam ponenda est pluralitas sine necessitate. — William of Ockham, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.
By being at college i meant i dont get out to work on my car much. But thanks i was just wondering if it would throw a SES light with low oil pressure. Ill have to find out what my check engine light is anyways i was hoping it would have something to do with the oil pressure but i guess not.
The OPSU is an easy swap-out, so go ahead and take care of that. Next, do the paper clip thing to read the codes, and find out what your SES light is about. Even easier to at least find out what the car is mad about, get it to confess its inner sins, even if fixing them sometimes is a bit more of a challenge (or, sometimes, not). At least you'll know.
__________________ Numquam ponenda est pluralitas sine necessitate. — William of Ockham, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.
ok, everyone on here says how easy it is to remove the oil pessure switch/sender.....well mine won't come out.
Am I seriously supposed to be able to get a wrench on it??
I have the filter off and can't get a wrench or pliers onto it from above or below....WTF???
Am I missing something here??
thanks rich. I will be ordering that socket this payday. I tried to get my oil pressure switch off but was damned if I could get to it w/a wrench or any type of pliers. That helps tremendously.
/side note anyone flushing their coolant system becareful with the petcock at the bottom of the radiator, my 91 is sitting in my works parking lot because "someone" twisted the petcock too hard when closing it and it broke. I now have the radiator out and am going to get it cleaned and fixed to re-install. Hopefully it will help solve some of my heat issues.
my guage is stuck all they way up, i switched out the cluster and no avail. still broke, i beilve its the sending unit, good thing to know about the tool before im out there for 5 hours going
My oil guage was working fine, until I changed the rotor and plugs on the car. In the process of doing that, I knocked loose a few hacked up wires near the battery, one was an alternator cable that took a while to figure out. Now the gauge is pegged to maximum and never moves. Does anyone know which wire is for the oil pressure gauge so I can try and trace it?
My oil gauge was working fine, until I changed the rotor and plugs on the car. In the process of doing that, I knocked loose a few hacked up wires near the battery, one was an alternator cable that took a while to figure out. Now the gauge is pegged to maximum and never moves. Does anyone know which wire is for the oil pressure gauge so I can try and trace it?
Thanks!
thats pretty much what mine does, gonna replace the sending unit first, then if that dont work, gonna go /emo naw j/p but hopefully the sending unit will fix it.
Btw whats the purpose of the oil pressure switch ? seen that while looking for the pressure sensor.
I believe the Oil Pressure Switch, after detecting oil pressure of 6 PSI or more, will send power to the fuel pump. The thinking, so I am told, is that if there is LESS than 6 PSI of oil pressure then something is wrong. Either you have an engine that stopped or you no longer have an adequate supply of oil. Thus the fuel pump should stop pushing fuel out of the fuel tank. One reason for this switch involves a traffic accident in which it would be unwise to allow the fuel pump to gush fuel out of the fuel tank when clearly the engine has stopped and fuel is not required to be flowing for any reason.
thats pretty much what mine does, gonna replace the sending unit first, then if that dont work, gonna go /emo naw j/p but hopefully the sending unit will fix it.
Btw whats the purpose of the oil pressure switch ? seen that while looking for the pressure sensor.
I was looking around my engine last night, and noticed a wire with a rubber boot on it that was't connect to anything. It was located kind of below the distribuer cap and plug wires on the driver's side. It connected to the the top of this cylinder looking thing. When I connected it my oil gauge began working again. So, before you go and start replacing sending units, check to make sure that wire is connected.
Yes i had the same thing as you, the wire with a boot was just dangling there, guess it was one of those things easily over looked. here are some pics for people who can use them
Yes i had the same thing as you, the wire with a boot was just dangling there, guess it was one of those things easily over looked. here are some pics for people who can use them
If this is still a problem or if anyone else is having this problem...
If there is no sign of binding or kinks, try the following. Pull the speedo cable most of the way out. Next get a lot, I mean be generous about it, a lot of multi-purpose grease (used for wheel bearings), slap that crap in the palm of your hand. Now, cup your hand around the end of the cable that goes back in first and start pushing the cable back in. While you're pushing the cable back in be sure plenty of grease gets on the cable. Also be sure not to force the cable too much or you'll end up with the kinks and bindings Apeiron spoke of.
I had the same bouncy speedo cable on my 78 Formula, did this and it fixed it.
What do you mean take the cable out? Do you mean pull the square steel cable out of the plastic sheath that runs from the transmission to the speedo? I didn't know you could do that. Can I just pop the cable off at the trans and pull straight from there without disassembling the dash? Then just push it back in? If that's true I'm going to go home and do that.
I know what you mean, it's a pain getting to the back of the gauges, only because there's a lot to take apart, including dropping the steering column. But on my 78 it was easy, there was less to take off.
Well crap, it just dawned on me, I was picturing doing this whole thing to an older car, it's setup different. On the 3rd gens all the gauges are in a pod that plugs into something else. So there is no cable at the back of the gauge itself. So at this point I don't know where the cable plugs into, I never cared to look. I have had my entire dash out (twice) for a swap and never cared to notice where it is or if there's even a cable going to the back of the dash at all. But, when you locate it, that's what you do. Pull the cable from the sleeve and grease it back in. It makes it move more freely keeping it from bouncing.
As for doing it the other way around, on the older bird I had I think it had to connect a certain way to the back of the speedo, but the end at the transmission just slid right in, I think it had a square end on it so you kinda turn it back and forth as you slide it the rest of the way in. So if the cable is "connected" to the location in the dash rather than "sliding" into position like at the transmission then forget it, go through the dash.
Last edited by SpeedyGeek; 01-30-2009 at 12:48 PM.
Yeah the cable runs to the back of the speedo in the gauge pod. You can disassemble the pod without doing anything with the steering wheel though. The biggest issue with taking the gauge pod out is that you have to lay on your back in the drivers side pan and reach up behind the dash and disconnect the speedo cable with the pod still assembled. Its a b*&^%. That's why I wanted to do it from the trans side. So your saying that it doesn't work that way?
I believe the Oil Pressure Switch, after detecting oil pressure of 6 PSI or more, will send power to the fuel pump. The thinking, so I am told, is that if there is LESS than 6 PSI of oil pressure then something is wrong. Either you have an engine that stopped or you no longer have an adequate supply of oil. Thus the fuel pump should stop pushing fuel out of the fuel tank. One reason for this switch involves a traffic accident in which it would be unwise to allow the fuel pump to gush fuel out of the fuel tank when clearly the engine has stopped and fuel is not required to be flowing for any reason.
FYI - Circuit has changed.
The power supplied by the FPS - fuel pump switch (operated by oil pressure) is backup power to the fuel pump in case the fuel pump relay fails. You will experience an extended start should the relay fail until OP closes the switch.
The ECM controls the fuel pump, no reference signal from the distributor and the ECM disables the fuel pump.
My '88 model doesn't have a collision fuel pump cutoff switch like fords, or any collision sensor of any kind.
Not germane to the matter at hand. Like I tell my college-age children (and they are tired of hearing it!!), sometimes you just gotta do what you gotta do, even if it seems a bit tough. 
i hate having something thats broke specially on my dash.
