Engine/Transmission (1998.5 - 2002) All sorts of codes

[lmills]

OK, I will start at the top. Yesterday while looking under the hood preparing for pyro/boost gauge install a big thunderstorm moved in while I had the hood up on my truck letting it cool down. I didn't think too much about it since I have washed the enigine off numerous times.



Well, I got up and hit the interstate this morning only to be greeted with problems. While climbing the mountain the truck lost power and oil pressure dropped shortly afterward. I didn't worry too much about the gauge since I know the sending units are prone to failure. I proceded to limp it up to the rest stop and shut it down. The pedal to the floor would only get me 50 mph. Upon shutting it down I checked everything over and called my sister for a ride. While waiting for them to pick me up I disconnected my EZ to try to trouble shoot the problems. The truck fired up and ran great, but the oil pressure was intermitent. Well I decided to drive it home once the oil pressure started to register again. Now I have the following codes.



237- map sensor low voltage

522 -oil pressure sensor low

1488- aux 5 volt supply output too low

5 volt supply voltage low

and the usual 1693



My question is do you think that moisture is causing all the problems? I have since reinstalled the EZ and it ran fine for a trip around the block, but then acted up again when I left the house a second time.

 

[catoiler]

Check to make sure all your grounds are in good order and there are no broken ones.

 

[parcher]

The 5 volt supply is the culprit, if the 5 volt supply is less than 5 volts then all of the sensors feeding off of it will be low. The computer does not trust the truck to be able to supply a constant 12 volts to sensors (and doesn't need 12 volts anyway) so it uses a regulated 5 volt supply to "power" the sensors the sensors ground this supply (variably) and the left over voltage or voltage drop is the value the computer reads as the sensor reading. So now you see how low supply voltage throws off all of the readings. i'm not sure if the oil pressure "sensor" uses the 5 volt supply or not but since it was the first thing you noticed and they are prone to fail I'd replace the iol pressure sensor first. One bad sensor that's totally shoted to ground will bring the entire 5 volt line down.

 

[krs]

Paul,

Wouldn't you suspect the EZ as having grounded? It goes to the map sensor and lmills lost power first, then oil pressure. The truck restores when the box is removed.

 

[parcher]

After this was pointed out to me I must agree, also I checked the 2002 service manual and the oil pressure switch is not 5 volt feeding sonsor. I am not familiar with many of the boxes some have on their trucks. Where would one mount a fueling box and how well are they sealed? I suspect that after adapting to the exttra power that testing for a while with it dis-connected is going to bite.

 

[lmills]

The box is about 1"x3"x4" approx. It is supposed to be a water tight box that is not affected by the elements. Most guys typically mount them on top of the power distribution box. It has two wires to hook up. The one is the data link, the other is the map sensor. The data link had moisture on it when I pulled it apart.





I just can't believe all this would come from having the hood up when it rained. I have washed the motor off at least 4-5 times and never had any problems like this.



I will find out for sure today. I have recleaned the connectors and put some dielectric grease on them. I have to go to Winchester VA to bring the travel trailer home. I am sure if it isn't fixed it will let me know while I am driving.