we have a 2003 R-1500 with 3.7 liter and it isXXXXXand we did a trany and a heater core the truck runs great just that the oil gauge sits at low and if you drive it then it will go all over the place we have replaced the op sender checked all the grounds in the engine compartment and also on the ecm and also we had done oil pressure test and at idle it was 70 psi and at 3000 rpm it was 90
Hello and welcome to JustAnswer!
Does the problem with the gauge only happen when the engine is hot or is it all the time? If it only happens when the engine is hot then you'll also need to check oil pressure with the gauge when the engine is hot and it would normally be acting up. With the pressures that you saw it's clear that the engine wasn't up to operating temperature, which is when you would expect more problems with actual oil pressure.
If the symptoms are identical then we should be able to rule the sender out. That would leave only a problem with it's wiring between the sender and powertrain control module (PCM), the PCM itself which isn't very likely, or it could be the instrument cluster.
If oil pressure can be verified as ok when the engine is hot then the next thing I would do is use a scan tool to see what the PCM is seeing for oil pressure. It's a switch rather than a sensor so you'll see it in one of two states, either pressure or no pressure. If you see pressure coming and going on a scan tool then you know it's a sender, wiring or oil pressure issue. If the PCM is seeing pressure even when the gauge drops out then it's going to be a cluster issue.
when we had looked at the scanner it had said the volts where at 4.98 and could not get it to go to zero and it was running at this time as far as the pressure I would have to look at it tomarrow when get to work
is there any way to check because when we look at the scanner and when the gauge goes up the volt seem to stay the same but it goes so fast that I don't think the scanner can catch it but if ok with you have to catch some zzzzzzzzs will talk to you tomarrow but if there is any thing you want me to check in the am put it down and I will reply it back to you
Ok I did look at the scanner and it said for oil pressure volts was 4.98 and the pressure was 0.0 and I also did a Actuator test and all of the gauges and lights had worked on the instrument cluster when I go down to the oil sender wire and used the power prob all it shows is ground. and I also checked the wire from the oil pressure switch and it was good witch was gray and yellow wire and I have been reading and it says that this should be a 3 wire connector but it is only 1 wire and that also shows 1 wire on wiring diag to
The sender is a single wire, it's a switch rather than a sensor.
Using a digital voltmeter, sender unplugged and key turned on what voltage do you see at the sender connector?
0.00 Volts at the connector and at the sender 0.00 volts to
I did do that and it showed 0 when checking resistance
ok sorry on my meter it starts with 1 and when you touch them together it goes to 0 so I would say then the problem is in the pcm would you agree
Ok thank you so much for your time that should get the boss off my but now to try to fig out how to tell the cu that they need to replace the pcm and get reflashed