Code P1453 - Secondary Air Pump Relay HELP

[m3f_acegp1]

Alright, so I keep getting this code and I can't figure out what to do. I am trying to get this car smog ready for CA and at this point I'm trying to avoid the SAP dummy connector.


Car: 1999 BMW M3 - Automatic (Stock S52)


Problem: Code P1453 -Secondary Air Injection Pump Relay Control Circuit Electrical





Steps Already Taken:

1. Step 1: Test Voltage at SAP Connector
   
   SAP Connector Voltages (Engine COLD):
   
   Key Off: 0.00V
   
   Key On: 4.35V
   
   Engine On: 2.05-3.00V
   
   
   I thought I was supposed to be getting 12 Volts at the connector so I replaced the SAP relay in the power distribution box but this did NOT solve the problem.
   
2. Step 2: Bench Test Bump
   
   Next I took out the pump and hooked it up directly to 12V and it works!
   
3. Step 3: Clear Codes and Restart Car from Cold
   
   This did not do anything the code came back immediately.

I am lost as to what could be causing this issue. Am I supposed to be getting 12V at the pump? What could cause the voltage drop and fluctuation?


Somebody help me please

[m3f_Porschetech]

check wiring and yes 12v should be present at both the relay and air pump (pin 30)

[m3f_acegp1]

check wiring and yes 12v should be present at both the relay and air pump (pin 30)

Alright so assuming the relay pin diagram is correct in the first post, I am not getting 12V at pin 30 ever. I measured voltage at the relay pins with the relay disconnected.



Key Off:

• Pin 30: 0
• Pin 85: 0
• Pin 86: 0
• Pin 87: 12.2V
• Pin 87a: 0

Key ON:

• Pin 30: 4.36V
• Pin 85: 0
• Pin 86: 12.0V
• Pin 87: 12.0V
• Pin 87a: 12.0V

Engine Running:

• Pin 30: 3.0V (fluctuating between 2.5 and 3.5V)
• Pin 85: 0
• Pin 86: 13.4V
• Pin 87: 13.4V
• Pin 87a: 13.4V

The secondary air pump is clearly getting power (albeit low) from Pin 30. What could cause the low voltage?



Is there any other relay or fuse in the system?

[m3f_Porschetech]

Alright so assuming the relay pin diagram is correct in the first post, I am not getting 12V at pin 30 ever. I measured voltage at the relay pins with the relay disconnected.


Key Off:

• Pin 30: 0
• Pin 85: 0
• Pin 86: 0
• Pin 87: 12.2V
• Pin 87a: 0

Key ON:

• Pin 30: 4.36V
• Pin 85: 0
• Pin 86: 12.0V
• Pin 87: 12.0V
• Pin 87a: 12.0V

Engine Running:

• Pin 30: 3.0V (fluctuating between 2.5 and 3.5V)
• Pin 85: 0
• Pin 86: 13.4V
• Pin 87: 13.4V
• Pin 87a: 13.4V

The secondary air pump is clearly getting power (albeit low) from Pin 30. What could cause the low voltage?


Is there any other relay or fuse in the system?

depends on what else that circuit shares or supplies. you'll need a wiring diagram now

[m3f_acegp1]

depends on what else that circuit shares or supplies. you'll need a wiring diagram now

I'm looking at the Bentley diagrams and I still am unable to trace this issue. It looks like the DME supplies ~4.3V to the relay which closes the contacts and theoretically switches 12V from the battery to the pump.



My problem is that the relay is somehow switching the 4.3V to the pump.



I tried a new relay and switched the one from the horn but still nothing.



I also replaced fuse 50 (F50) under the dash which powers the pump valve and that didn't solve my issue.



Any other thoughts?

[m3f_acegp1]

I installed a new salmon 5 prong relay and the air pump works.



My problem now is that the pump will not shut off.



Here is the scenario:

1. I start the car (engine cold) and the air pump turns on
2. I wait 5 minutes until the car is warmed up and I turn the car off (Key OFF)
3. The pump stays on for ~3 seconds and then turns off and then 3 seconds later clicks back on!

This must be a wiring issue but my grounds look good.



Any thoughts?

[m3f_daytonaviolet]

when its car is on and pump is active, 30 and 87 should be closed and 12V goes to the pump. when key off, it should go to 87A. but why is there 12V on 87A?


are you sure you have the correct 5 pin relay. some relays short 87 and 87A and some dont.