Testing the MAP/BARO switch solenoid valve (and the resulting P1105 trouble code) on your Nissan Pathfinder isn't hard and it's something you can do yourself.
In this tutorial, I'll show you what you need to do to find out if it's bad (or not) in a step-by-step way.
NOTE: Although this tutorial is written with the Nissan 3.3L equipped Pathfinder in mind... it also applies to the 3.5L equipped Pathfinder (QX4) and 3.3L/3.5L Frontier, since the same type of BARO/MAP switch solenoid valve is used on both vehicles. For more specifics, see the ‘Applies To:’ box on the right.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Solenoide De Presión MAP/BARO (1996-2004 3.3L Nissan Pathfinder) (at: autotecnico-online.com).
MAP/BARO Switch Solenoid Valve Diagnostic Essentials
What it does: The MAP/BARO switch solenoid valve is tasked with the job of providing manifold vacuum to the MAP sensor a few seconds after the engine starts up. Why?
... So that the MAP sensor can take a barometric pressure reading before the MAP/BARO switch feeds it intake manifold vacuum.
So, when it doesn't switch from barometric pressure to manifold vacuum pressure (after your Nissan Pathfinder starts up), your Nissan Pathfinder's (or Frontier's) PCM lights up the check engine light and sets a P1105 trouble code and MAP sensor code.
Vacuum hose routing: Using the illustration above, here are the MAP/BARO switch solenoid valve vacuum hose specifics:
- Vacuum hose port A
- To air cleaner box.
- Vacuum hose port B
- To MAP sensor (called the absolute pressure sensor by Nissan).
- Vacuum hose port C
- Manifold vacuum.
Common Problems: The most common causes of a P1105 MAP/BARO switch solenoid valve trouble code are:
- Misrouted vacuum hoses.
- Broken vacuum hoses.
- Failed MAP/BARO switch solenoid valve.
What you need to do first: Before you start testing the MAP/BARO switch solenoid valve itself... you need to make sure that:
- All vacuum hoses that connect to the solenoid valve are routed correctly.
- The vacuum hoses that connect to the solenoid valve are not broken or leaking vacuum.
- The vacuum hose that connects to the vacuum port labeled with the letter C (in the illustration above) has vacuum with the engine running.
- MAP sensor is getting vacuum a few seconds after the engine starts.
- If the MAP sensor is NOT getting vacuum, then proceed to TEST 1.
TEST: Bench Testing The MAP/BARO Switch Solenoid Valve
Now that you've checked that all of the vacuum hoses (that connect to the MAP/BARO switch solenoid valve) are routed correctly, that the switch is being fed vacuum and the MAP sensor is not getting vacuum (after the engine has started)...
... The next step is to bench test the solenoid valve itself to see if it's fried (or not).
Bench testing the MAP/BARO switch solenoid valve simply involves removing it and applying power and Ground to it (with jumper wires). And in this test step I'll show you how.
Here's what you need to do:
Remove the MAP/BARO switch solenoid valve from its location underneath the MAP sensor.
Apply battery voltage to terminal 1 of the solenoid valve using a jumper wire.
NOTE: Use a fused jumper wire to apply 12 Volts from your Nissan Pathfinder's battery to terminal 1.
Apply battery Ground to terminal 2 of the solenoid valve using a jumper wire.
With battery power and Ground applied:
1.) Air should now pass between ports A and B.
2.) Air should NOT pass between ports B and C.
Remove battery Ground from terminal 2 of the solenoid.
With battery power and Ground removed:
1.) Air should NOT pass between ports A and B.
2.) Air should pass between ports B and C.
Let's take a look at your test results:
CASE 1: Air passed (and not passed) as specified. This test result tells you that the MAP/BARO switch solenoid valve is OK and not the cause of the P1105 diagnostic trouble code.
If the P1105 trouble code is still present, then your next step is to check that the two circuits that feed power and the activation signal from the PCM are not shorted to Ground or ‘open’. Although this is beyond the scope of this tutorial, you have eliminated the MAP/BARO switch solenoid valve as being defective.
CASE 2: The solenoid valve did not work as specified. This test result tells you that the MAP/BARO solenoid is fried and needs to be replaced with a new one.