I have a 2001 4wd tacoma and my check engine light is on continuously now. can i get a trouble code by placing a jumper wire between 2 terminals and if so which terminals and where are they located?

Connect white (test lead) and black (ground lead) wires that are branched from harness approximately eight inches from ECM. After leads are grounded, the "Check Engine" light will flash the diagnostic trouble codes. The DTC's are indicated by the flashing CEL.
FLASH, FLASH, pause, FLASH, FLASH, FLASH = Code 23.
If only one diagnostic trouble code is stored, the DTC will repeat continuously until test leads are disconnected. If more than one diagnostic trouble code is stored, each DTC will repeat three times, starting with the lowest, then proceed to the next DTC. After all DTC's have been displayed, the pattern will repeat.I-MARK 84-85

Connect male and female test leads taped into wire harness near ECM. After leads are connected, the "Check Engine" lamp will flash the trouble codes. The DTC's are indicated by the flashing CEL.
FLASH, FLASH, pause, FLASH, FLASH, FLASH = Code 23.
If only one diagnostic trouble code is stored, the DTC will repeat continuously until test leads are disconnected. If more than one diagnostic trouble code is stored, each DTC will repeat three times, starting with the lowest, then proceed to the next DTC. After all DTC's have been displayed, the pattern will repeat.
86-87 Impulse located near the ECM connector, is used to actuate the Engine Control Module (ECM) trouble code memory within the module. Two terminals (A and C) of this connector are used to activate the diagnostic trouble code system in the ECM. With the ignition switch turned On, engine Off, connect a jumper wire between terminals A and C. The "Check Engine" lamp will begin by flashing a DTC 12. DTC 12 = flash, pause, flash, flash. There will be a longer pause and a code 12 will repeat two more times. This code indicates the self-diagnostic system is operating. The cycle will then repeat until the engine is started or the ignition is switched Off. In most cases, DTC's will be checked with the engine running since no DTC's other than DTC 12 or 51 will be present without the engine running. Remove jumper wire from ALDL connector before starting engine. Reconnect jumper wire after engine is running.

Throttle Body Fuel Injection

The ECM test connection is located under the center console.
A built-in, self diagnostic system will identify problems in the throttle body fuel injection system. When a problem is detected, the diagnostic system will illuminate the "Check Engine" light.
When the engine is started, the Check Engine light should turn off.. If the light remains lit, the self diagnostic has detected a problem. To determine where the problem exists, ground the "Test" terminal of the connector with the ignition On, engine Off and watch the check engine light. Each DTC will flash three times (lowest to highest).

The check engine light is used to blink out the trouble codes. The diagnostic connector is usually under the hood on driver's side, back near the firewall. Sometimes under the driver's dash. Use a jumper wire and connect terminals TE1 and T1. Then turn key to on, not start, and the check engine light will blink out the trouble codes. If no codes are present, the check engine light will stay on constantly. Remove jumper wire when diagnostics completed. To clear codes after repairs, disconnect the negative battery terminal for one minute, and then reconnect.
This site has Toyota code explanations:

The P0401 means the problem at exhaust gas recirculation flow insufficient detected.
NEXIQ 125032

Hi, the problem may be at the TPS or the MAP sensor. First extract the trouble code following instructions below. Then troubleshoot the indicated signals/sensors.

Fig. Fig. 1: ALDL connector-1994 models

Listings of the trouble for the various engine control system covered in this guide are located in this section. Remember that a code only points to the faulty circuit NOT necessarily to a faulty component. Loose, damaged or corroded connections may contribute to a fault code on a circuit when the sensor or component is operating properly. Be sure that the components are faulty before replacing them, especially the expensive ones. The Assembly Line Diagnostic Link (ALDL) connector or Data Link Connector (DLC) may be located under the dash and sometimes covered with a plastic cover labeled DIAGNOSTIC CONNECTOR.

1. On all 1994 models the diagnostic trouble codes can be read by grounding test terminal B . The terminal is most easily grounded by connecting it to terminal A (internal ECM ground). This is the terminal to the right of terminal B on the top row of the ALDL connector.
2. Only 1995 models equipped with a PCM use the OBD I system. All other 1995 and later models use the OBD II system. The diagnostic trouble codes on 1995 OBD I systems can be read by grounding test terminal 6 . The terminal is most easily grounded by connecting it to terminal 5 (internal ECM ground).
3. Once the terminals have been connected, the ignition switch must be moved to the ON position with the engine not running.
4. The Service Engine Soon or Check Engine light should be flashing. If it isn't, turn the ignition OFF and remove the jumper wire. Turn the ignition ON and confirm that light is now on. If it is not, replace the bulb and try again. If the bulb still will not light, or if it does not flash with the test terminal grounded, the system should be diagnosed by an experienced driveability technician. If the light is OK, proceed as follows.
5. The code(s) stored in memory may be read through counting the flashes of the dashboard warning lamp. The dash warning lamp should begin to flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the VCM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent.
6. After Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest.

The order of codes in the memory does not indicate the order of occurrence.

1. If there are no codes stored, but a driveability or emissions problem is evident, the system should be diagnosed by an experienced driveability technician.
2. If one or more codes are stored, record them. Refer to the applicable Diagnostic Code chart in this section.
3. Switch the ignition OFF when finished with code retrieval or scan tool readings.

MAP sensor tests:
TESTINGSee Figures 1, 2 and 3

Fig. Fig. 1: Typical Manifold Absolute Pressure (MAP) sensor wiring diagram (wire color, terminal identification/location may vary on certain models)

1. Backprobe with a high impedance voltmeter at MAP sensor terminals A and C .
2. With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
3. If the voltage is not as specified, either the wiring to the MAP sensor or the VCM may be faulty. Correct any wiring or VCM faults before continuing test.
4. Backprobe with the high impedance voltmeter at MAP sensor terminals B and A .
5. Verify that the sensor voltage is approximately 0.5 volts with the engine not running (at sea level).
6. Record MAP sensor voltage with the key ON and engine off.
7. Start the vehicle.
8. Verify that the sensor voltage is greater than 1.5 volts (above the recorded reading) at idle.
9. Verify that the sensor voltage increases to approximately 4.5. volts (above the recorded reading) at Wide Open Throttle (WOT).
10. If the sensor voltage is as specified, the sensor is functioning properly.
11. If the sensor voltage is not as specified, check the sensor and the sensor vacuum source for a leak or a restriction. If no leaks or restrictions are found, the sensor may be defective and should be replaced.

Fig. Fig. 2: Using jumper wires and a high impedance voltmeter test between MAP sensor terminals A and C with the key ON and engine off. The voltage should be approximately 5 volts

Fig. Fig. 3: Next test between MAP sensor terminals A and B with the key ON and engine off. The voltage should be approximately 0.5 volts

MAP sensor


Throttle position sensor test
TESTINGSee Figures 1, 2 and 3

1. Backprobe with a high impedance voltmeter at TPS ground terminal and 5 volt reference signal terminal.
2. With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
3. If the voltage is not as specified, either the wiring to the TPS or the VCM may be faulty. Correct any wiring or VCM faults before continuing test.
4. Backprobe with a high impedance voltmeter at the TP signal terminal and the sensor ground terminal.
5. With the key ON and engine off and the throttle closed, the TPS voltage should be approximately 0.5-1.2 volts.
6. Verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed. Make sure to open and close the throttle very slowly in order to detect any abnormalities in the TPS voltage reading.
7. If the sensor voltage is not as specified, replace the sensor.

Fig. Fig. 1: Common Throttle Position Sensor (TPS) wiring diagram (wire color, terminal identification/location may vary on certain models)

Fig. Fig. 2: Using jumper wires and high impedance voltmeter, test between the sensor ground and reference terminals, the voltage should be approximately 5 volts

Fig. Fig. 3: Next test between the sensor signal and ground terminals, verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed

Code 11 means no distributor reference signal detected during cranking. Check the circuit between the Distributor and PCM (computer). Also, keep in mind the following operations/tests apply to these relays only: Automatic Shutdown (ASD) , Fuel Pump and Ballast Bypass. For operations/tests on all other relays refer to the appropriate test.

OPERATION:
The relay terminal numbers can be found on the bottom of the relay.
Terminal number 30 is connected to battery voltage and can be switched or B + (hot) at all times.
Terminal number 87A is connected (a circuit is formed) to terminal 30 in the de-energized (normally OFF) position.
Terminal number 87 is connected (a circuit is formed) to terminal 30 in the energized (ON) position. Terminal number 87 then supplies battery voltage to the component being operated.
Terminal number 86 is connected to a switched power source.
Terminal number 85 is grounded by the Engine Controller.

TESTING:
Remove relay before testing.
Using an ohmmeter, perform a resistance test between terminals 85 and 86. Resistance value (ohms) should be 75 ±5 ohms for resistor equipped relays.
Connect the ohmmeter between terminals number 87A and 30. Continuity should be present at this time.
Connect the ohmmeter between terminals number 87 and 30. Continuity should not be present at this time.
Use a set of jumper wires (16 gauge or smaller). Connect one jumper wire between terminal number 85 (on the relay) to the ground side (-) of a 12 Volt power source.
Attach the other jumper wire to the positive side (+) of a 12V power source. Do not connect the jumper wire to relay at this time.

CAUTION: Do not allow the ohmmeter to contact terminals 85 or 86 during these tests. Damage to ohmmeter may result.

Attach the other jumper wire (12V +) to terminal number 86. This will activate the relay. Continuity should now be present between terminals number 87 and 30. Continuity should not be present between terminals number 87A and 30.
Disconnect jumper wires from relay and 12 Volt power source.

If continuity or resistance tests did not pass replace relay. The Powertrain Control Module (PCM) and connector are located in the engine compartment, mounted to the inner fender, next to the air cleaner housing (click image fo zoom).
DTC 11 - No reference signal during engine cranking. No camshaft reference signal was detected during engine cranking.
DTC 12 - Battery disconnect. Battery input to PCM disconnected during last 50 key starts.
DTC 42 - ASD relay control circuit. An open or shorted condition detected in the auto shut down relay circuit.



Hope helps.

First check power to the coil. Pull the connector off and probe the connector terminal from the pink wire with a 12 volt test light. Connect the test light clip to a ground point/bolt on the engine. The test light should come on when the ignition switch is on. If not, suspect the ECM-1 fuse is bad or the ignition switch is bad.
If there is power to the coil, next test the coil. Run a jumper from the battery positive terminal to the pink terminal on the coil itself. Pull the coil wire off the distributor and place the wire close (within 1/4 inch) to a ground point on the engine. Then, briefly touch a jumper from the black/white coil terminal to engine ground. The coil should release a spark. If not, replace the coil.
If the coil is good, suspect the crankshaft position sensor is bad or loose. I'm assuming your engine light is off, but the sensor can fail without setting the engine light. If the engine light is on, see if you can get a scan to see if a crankshaft sensor trouble code is set.
Please let me know if you have any questions.

This is straight from Haynes Repair Manual for 1989-1997 Isuzu Amigo/Rodeo/Honda Passport (book # 47017:
The 12 pin Assembly Line Data Link (ALDAL) terminal is located under the dash on the driver's side on 3.1L engines. To retrieve the trouble codes, connect a jumper wire to terminals A and B. It may be covered with a plastic cover. They suggest using a paper clip to jumper the two terminals-then turn ignition switch to ON position (NOT ENGINE START). Check engine light on dash will flash-one flash-a pause-then two short flashes-indicating code 12-diagnostic mode. After self checking-if there are any trouble codes-the light will flash proper codes using mentioned method.Note the flash code then call a shop with your info for what ails your Rodeo.

if you go to the auto parts store, they may sell a key that jumps out the dlc connector under the dash. the light will blink for the code.#

go to autozone have them scan it and then clear it record the trouble code and then clear it another option is disconnect the battery both positive and negative and make a jumper wire between the 2 terminals make sure that you disconect the battery very importan

The throttle position sensor has an idle switch in it that tells the car's computer that the throttle is positioned at idle. If the idle switch sticks in the idle position, the computer will not allow the engine to rev more than 2500 rpm. In your case, I think the switch is stuck.

First, see if you can get the trouble codes to come up. Rig a jumper wire and jump between the "T" terminal and the "E1" terminal in the car's "Diagnostics" box. It is a small black box on the driver's side of the engine compartment near the battery. Open the lid and on the inside of the lid it has a map of the terminals.

Once you hook up the jumper wire, turn the ignition switch to on but do not start the car. If there are codes, the check engine light (orange) will blink the 2 digit code. It blinks the first digit, pauses, then blinks the second digit. The code for the throttle position sensor is code "41". That is, four blinks...pause...then one blink. If this code comes up, change the throttle position sensor. (If there are no codes, the check engine light will steadily blink once per second until you turn the key to off.) Don't forget to remove the jumper wire when you are finished.