Test TC-4A - No Change In Map From Start To Run (DTC 13)

WARNING: This page is about a different car, the 1995 Jeep Wrangler, 1995 Jeep Grand Cherokee, and 1995 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Perform TEST TC-1A before proceeding with this test. For connector terminal identification, see CONNECTOR IDENTIFICATION at beginning of article. For wiring diagrams, see WIRING DIAGRAMS at the end of this article. Perform TEST VER-2A after each repair.

Turn ignition on and engine off. Using scan tool, erase trouble code messages. Start engine. Allow engine to idle for 30 seconds. With engine running, read trouble code messages using scan tool. If scan tool displays NO CHANGE IN MAP FROM START TO RUN, go to next step. If scan tool does not display NO CHANGE IN MAP FROM START TO RUN, go to step 5).
Using scan tool, set engine speed to 1500 RPM. With engine running at 1500 RPM, read scan tool MAP sensor voltage. While monitoring MAP sensor voltage, wiggle MAP sensor connector and wiring harness. If engine does not stall and MAP sensor voltage does not become erratic, go to next step. If engine stalls or MAP sensor voltage becomes erratic, inspect all related wiring and connectors and repair as necessary.
Snap throttle open and closed while monitoring scan tool. If engine vacuum does not rapidly drop to less than one in. Hg, inspect MAP sensor vacuum line for restrictions. Repair restrictions as necessary. If vacuum line is okay, replace MAP sensor. If engine vacuum rapidly drops to less than one in. Hg, go to next step.
Condition required to set code is not present at this time. NO CHANGE IN MAP FROM START TO RUN fault sets if too small a difference is seen between barometric pressure at key on and manifold vacuum after engine start. Possible causes are: restricted or leaking vacuum/pressure hose to MAP sensor, ice in MAP sensor or passage, MAP sensor failure or PCM failure.
Turn ignition on and engine off. Using a vacuum tee, connect a vacuum gauge into MAP sensor vacuum line. Start engine and, while at idle, read vacuum gauge. If vacuum was not zero in. Hg at idle, go to next step. If vacuum was zero in. Hg at idle, repair vacuum line for a leak or restriction to MAP sensor.
While monitoring vacuum gauge, snap throttle open and closed. If vacuum did rapidly drop to zero in. Hg, go to next step. If vacuum did not rapidly drop to zero in. Hg, repair restricted vacuum line.
Turn ignition off. Disconnect Manifold Absolute Pressure (MAP) sensor connector and ensure connector is clean and not damaged. Turn ignition on. Using scan tool in voltmeter mode, check voltage on MAP sensor connector terminal No. 3, 5-volt supply circuit (Violet/White wire). If voltage is less than 4 volts, repair open or short in 5-volt supply circuit. If voltage is more than 4 volts, replace MAP sensor.