Vacuum pump and BIU

A misfire could be caused by a bad , clogged fuel injector . A vacuum leak . How are you reading a misfire ? A code ? A dirty mass air flow sensor can cause misfires . Low fuel pressure ,clogged fuel filter . When you replaced the fuel pump did you replace the ceramic sending unit resistor card with a new one ?
Fuel Gage
The IPC displays the fuel level as determined by the PCM- engine computer. The IPC -instrument panel cluster receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:
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The PCM detects a malfunction in the fuel level sensor circuit.

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The IPC detects a loss of class 2 communications with the PCM.

When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.
Reviewing the fuel system description will further explain how the system functions. Refer to Fuel System Description .
Do you know about class 2 serial data communication .
Do

the vacuum pipe to the alternator is connected to the vacuum pump on the alternator to get vacuum for the brake booster
the wires will be to put the low vacuum light on in the dash
as to the vacuum line to the pump , you may have a vacuum operated governor control for the fuel pump
best to ask an accredited diesel shop or check the workshop manual which will explain the operation on the pump

You have farly serious transmission issues here. see the dealer.

A shop with a Tech2 Scanner can operate the air pump and solenoid. Or you can verify the solenoid valve by having power and ground, the valve should flow vacuum to the air valves, and the valves should operate (open) with vac going to them. Any dealer or AC Delco parts house should have the solenoid if needed.

Check the vacuum booster by purchasing a hand pump vacuum leak down tester disconnect the vacuum booster vacuum line from engine and pump up the handle on the tester to acheive at tleast 15 lbs of vacuum then stop pumping the gauge needle should not come down if it does the vacuum booster must be replace its internal rubber diaphram has a leak this would explain the poor or weak brake performance.

The pump is located on the passenger side of the engine compartment, back by the firewall. Look in the middle of the firewall by the cowl and you'll see a small plastic line going into the cowl. follow it back and you will come to a T fitting. Follow it to the passenger side and it will go into the Vacuum pump that controls the Cruise control.If you follow it to the other side, it goes under the Battery box. this is where the Servo for the cruise is located. Check the lines for small cracks, wear spots or even breaks. The plastic line can get beaten up pretty easily.
The easy way to see if it is your vacuum pump, turn the key on and listen. you will hear 2 distinct sounds. The first sound will stop in about 15 - 20 seconds. (fuel pump?) the second sound is the vacuum pump. If it turns off in 45 seconds to a minute (or slightly longer) the vacuum pump is probably ok, as are the plastic lines. The sound of the pump stopping means that vacuum has been achieved and is holding vacuum. If it keeps running, the pump is bad or the lines have a break in them. If the lines have had a hole in them for a long time, the diaphragm in the pump will have gone south. This is not a servicable part and the pump will have to be replaced. The pump is available from a dodge dealer but most likely the parts guy will not have a clue as there is no picture in their manual and a very poor description. When talking to them ask for a "03 Ram 2500 CUMMINS Cruise vacuum pump"
The part costs $212.70

Hello, I know exactly what your talking about! and why no one else did... The error code is being displayed on your trip/odo LCD screen at the bottom of your right gauge pod if I remember correctly. Only, it\'s not Er 66... it\'s (Er bb) which is a malfunction with your vacuum pump system. I truly hope this is the same concern you are asking about, if so I am happy I could help. If it is a different problem please let me know so I can look into this matter further. I\'ve added an "error chart guide" so you will have proof this time when/if you decide to return to the dealer... Good luck!! and I hope this info helps...(subytech1)...

fuel cap is just one of the causes. Here are 2 others:

• possible vacuum leak
• NVLD switch is stuck or malfunctioning

NVLD switch communicates with your car's computer. A bad switch will throw a P0457 error code. Check for a vacuum leak 1st but if none is found, the NVLD switch should be changed.
Below is a link that explains more thoroughly what the module does; I do wish you the best of luck with your Neon and hope you found this information helpful. Take care!
http://www.search-autoparts.com/searchautoparts/article/articleDetail.jsp?id=377511&sk=&date=&pageID=3

This is a communication error with the BIU (body integrated unit). Need to take to the dealer, possible that the ECU needs to be replaced to fix this issue. It should be covered under the federal emmission wrty.

Most of the time it’s a Fuse, PVH,(Pulse Vacuum Hublock) ,Vacuum line or Vacuum pump.
ESOF 4WD Trouble shooting It is easier to trouble shoot the system if you have a “Mityvac” vacuum pump. Turn the ignition switch to run (you don’t have to start the truck) and the air controls to vent and the fan control to low. If the truck’s vacuum pump comes on wait until it stops running before each test (open the hood and you’ll hear it better). First you need to remove both lines (left and right vacuum lines) from the hubs. Plug the passenger’s side line and attach the vacuum pump to the driver’s side line. Switch the dash controller to 4WD high. The vacuum gauge should go to 10 in.-Hg. or higher. (It should hold the vacuum at 10 in.-Hg. or higher for 45 seconds on engage and 15 seconds on disengage.) Repeat the test plugging the drivers side and testing the passengers side. If you have the right amount of steady vacuum the problem is probably in the hubs. If you do not have the right amount of vacuum or it is bleeding off, plug the lines back on the hubs and go to the next step. Second remove the vacuum lines from the PVH (Pulse Vacuum Hublock). This is the solenoid located on the passenger side fender well behind the battery and in front of the vacuum pump. Plug the vacuum tester into the lower hose and wait for the vacuum pump to build back up and shut off. The vacuum gauge should read and hold steady at 10 in.-Hg. or more. If it does, the vacuum reservoir should be fine and not leaking, so go on to the next step. Third, plug the bottom line back to the bottom of the solenoid and hook the vacuum gauge to the top barb of the solenoid (not the vacuum line but to the solenoid itself). Try switching between 2WD and 4WD again. The gauge should read 10 in.-Hg. for 45 seconds on engage and for 15 seconds on disengage. If it doesn’t it is probably the solenoid (PVH) on the fender that needs replacing. This was my problem so this was as far as I have gone. If all these things check out, THEN you need to go to the hubs and check them for leaks with the vacuum tester. Most of the time it’s a fuse, PVH, vacuum line or vacuum pump and not the hubs. Does your ac/heater work properly when you switch modes (IE linger before going in?) or sometimes stay on defrost? These trucks have a vacuum pump that controls it and the auto hubs.If the vacuum pump or hose,fails those are easy to see symptoms.


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