Vacuum pump issue?

[Mopar]

I recently did a new bumper and had to relocate the vacuum pump. Relocated it to near the PCM.

I cut the electric lines at the pump and extended them. All connections are good and I ran 12v directly to the pump and it runs and I verified it pulls full vacuum. So the pump and check valves are all in place and working.

I turned the key to run but didn't start it and then pumped the brake pedal a few times. It ran out of vacuum assist but the pump never came on.

I tried disconnecting the sensor at the brake booster to force it to “see” low vacuum and it still never came on.

Otherwise, in normal driving the brakes work fine and no check engine lights. Any thoughts?

I am not the original owner (3 prior) so I don’t know exactly what mods have been done. I haven’t started using JScan yet but is it possible someone turned off the vacuum pump using JScan?

 

[Mopar]

Hello anyone on this forum??

 

[JeepJeezy]

Did you have vacuum assistance the whole time with just key on before the move? Honestly, now I'll have to check if I do without the motor running and just the key on.

 

[Mopar]

Did you have vacuum assistance the whole time with just key on before the move? Honestly, now I'll have to check if I do without the motor running and just the key on.

I don’t know. I assumed everything worked before I relocated it. Everything was working fine before I relocated it and it’s all working fine now in normal operation. But, I can’t seem to get the pump to turn on unless I connect power directly to the pump plug. Then, it works fine. So, I am confident my connections are good.

My brakes work fine for normal driving. Been working through some lift issues from the previous owner so haven’t been able to really off road it at all. But, that’s coming. Been ordering parts as I find issues.

 

[pc1p]

Couldn't find anything definitive, it seems that the pump runs as needed while the engine is running but may not at other times. It is only supposed to run for a few seconds at start then as determined by the PCM:

From the 2014 FSM:

The Electric Vacuum Pump (EVP) system is installed to provide supplemental vacuum to the brake booster when the engine vacuum supply is low. The vacuum pump is connected to the engine and the brake booster through a series of hoses and one-way flow check valves. A pressure senor, mounted in the brake booster, provides information to the Antilock Brake System (ABS) module, then the vacuum level is sent over CAN to the Powertrain Control Module (PCM). The PCM modulates the EVP operation to maintain the brake booster vacuum within a given range. This system ensures that the customer experiences a consistent brake pedal feel under all driving conditions.

A two wire electrical connector is used to supply power and ground for the vacuum pump. Operating voltage is between 9V - 16V. Control of the vacuum pump is provided by the Powertrain Control Module (PCM) using a low side driver to a normally open relay (coil side). The relay coil side power is from a fuse in the under hood PDC. The switched power circuit to the vacuum pump relay is wired directly from the battery through an inline fuse holder located below the remote battery post connection on the RH side in the engine compartment. The relay is located on the LH shock tower in the engine compartment.

The PCM monitors the Manifold Absolute Pressure (MAP) sensor and when the signal indicates low engine vacuum the PCM will cycle the vacuum pump as necessary to add vacuum to the power brake booster. The vacuum hoses are connected between the vacuum pump, the engine manifold (for MAP sensor signal), and the power brake booster vacuum sensor (on the brake booster). When the PCM cycles the vacuum pump on, the PCM monitors the MAP sensor and if the vacuum signal does not indicate a rising vacuum then DTCs will be set. Additionally, the Antilock Brake System (ABS) module monitors the vacuum at the brake booster vacuum sensor and DTCs will also set in the ABS module.

https://www.wranglerforum.com/threa...r-up-to-15-seconds-almost-every-time.2375389/

 

[BLACKJKU]

Couldn't find anything definitive, it seems that the pump runs as needed while the engine is running but may not at other times. It is only supposed to run for a few seconds at start then as determined by the PCM:

From the 2014 FSM:

The Electric Vacuum Pump (EVP) system is installed to provide supplemental vacuum to the brake booster when the engine vacuum supply is low. The vacuum pump is connected to the engine and the brake booster through a series of hoses and one-way flow check valves. A pressure senor, mounted in the brake booster, provides information to the Antilock Brake System (ABS) module, then the vacuum level is sent over CAN to the Powertrain Control Module (PCM). The PCM modulates the EVP operation to maintain the brake booster vacuum within a given range. This system ensures that the customer experiences a consistent brake pedal feel under all driving conditions.

A two wire electrical connector is used to supply power and ground for the vacuum pump. Operating voltage is between 9V - 16V. Control of the vacuum pump is provided by the Powertrain Control Module (PCM) using a low side driver to a normally open relay (coil side). The relay coil side power is from a fuse in the under hood PDC. The switched power circuit to the vacuum pump relay is wired directly from the battery through an inline fuse holder located below the remote battery post connection on the RH side in the engine compartment. The relay is located on the LH shock tower in the engine compartment.

The PCM monitors the Manifold Absolute Pressure (MAP) sensor and when the signal indicates low engine vacuum the PCM will cycle the vacuum pump as necessary to add vacuum to the power brake booster. The vacuum hoses are connected between the vacuum pump, the engine manifold (for MAP sensor signal), and the power brake booster vacuum sensor (on the brake booster). When the PCM cycles the vacuum pump on, the PCM monitors the MAP sensor and if the vacuum signal does not indicate a rising vacuum then DTCs will be set. Additionally, the Antilock Brake System (ABS) module monitors the vacuum at the brake booster vacuum sensor and DTCs will also set in the ABS module.

https://www.wranglerforum.com/threa...r-up-to-15-seconds-almost-every-time.2375389/

Would explane why his brakes still work good, if the brakes didn't or had a hard pedal then he would know the pump wasn't working. When the pump kicks on when first started would be because the vacuum in the booster was to low.