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2 RELAYS IN FRONT OF TIPM ONE FOR THE RADIATOR FAN WHAT IS THE OTHER ONE?

7K views 3 replies 2 participants last post by  AllanC 
#1 ·
One of the relays that is mounted right by the headlight which now has the part number
56007080AB is what I have replaced several times thinking that it is the radiator high speed relay.

There is another square relay right below the TIPM or right in front of it but, below it.
It has the part number 68093292AA. I have never replaced this relay and I am wondering exactly what does it do?

Please advise? does this relay have any relation to the radiator high speed fan relay?
 
#4 ·
. . . . Still undetermined but it may be the Vacuum Pump Relay. . . .
Pink/light green trace wire is helpful. Two wires for the control circuit and 2 wires for the load circuit. Yes this appears to be a vacuum pump relay. I would not have expected such a device to be on the vehicle. With climate control and emissions devices electrically controlled, not much else that uses vacuum. Now 10 - 15 years ago and older, climate control and other emission control features were vacuum actuated. Here is a description I found on operation of the electric vacuum pump system.

When you release the accelerator and apply the brake pedal, engine vacuum goes high because the throttle valve has closed. And when stopping and requiring brake booster assist, you want high engine vacuum. When you accelerate the throttle valve opens and engine vacuum decreases. But you do not use the brake booster while accelerating. Also the large reservoir built into the brake booster gives 2 - 3 vacuum assisted stops before vacuum is depleted. Is this another instance of engineers over-thinking the situation, adding complexity and future aggravation with component failure???

OPERATION
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 sensor, 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.
 
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