2.5L Idle Speed-up Jumper harness

[eaglescout526]

For those of us who have them/recently acquired them:

 

Here are the bulletin pages for your reading leisure to see if you have this present issue:

 

BODY CODE LEGEND

 

MJ - COMANCHE

XJ - CHEROKEE

YJ - WRANGLER

 

SYMPTOM/CONDITION

 

Some 1987-1989 Jeep vehicles equipped with the 2.5L engine may exhibit a vibration at low idle speed. This condition will be most noticeable once the engine has reached its normal operating temperature.

 

This vibration condition can be improved be installing an idle speed jumper harness in the ECU circuit. This will increase the idle RPM be changing the idle mode signal to the ECU

 

DIAGNOSIS

 

Allow the engine to reach normal operating temperature. Connect a tachometer to the engine ignition. Set the parking brake and place the transmission in neutral. Start the engine and verify that the engine is at the idle and above a minimum of 750 RPM. Using the accelerator, raise the engine idle to 950 RPM. If the vibration complaint is now satisfied, then proceed with the following repair procedure.

 

If the initial idle speed is below 750 RPM or the vibration complaint is not satisfied at 950 RPM, the cause must be determined prior to performing this repair procedure. Determine the cause by performing a vehicle test with the DRB II or the MS 1700 Tester, and by visual inspection of components, such as vacuum hoses and connections, powertrain mounting and exhaust system.

 

 

PARTS REQUIRED

 

Idle Speed Harness

 

          1987-89 2.5L Wrangler                          PN 56002-101

 

          1987-89 2.5L Cherokee,                        PN 83100-070

          Wagoneer, Comanche

 

REPAIR PROCEDURES

 

1.       Locate the Electronic Engine Control (EEC) Harness Connector (A) under hood. The connector can be found on the right wheel well near the fuel pump and B+ latch relays on Cherokee, Wagoneer and Comanche models, and between the battery and charcoal canister on Wrangler models.

 

 

 

 

NOTE:    FOR THE WRANGLER, THE CONNECTOR (A) WILL BE A 4 TERMINAL CONNECTOR (FIGURE 1). THE CONNECTOR (A) FOR THE CHEROKEE, WAGONEER AND COMANCHE WILL BE A 6 TERMINAL CONNECTOR (FIGURE 2).

 

 

2.   Disconnect the EEC Connector and install the idle speed jumper harness (B) between the EEC harness connector. Figure 3 shows the Wrangler with idle jumper harness installed. Figure 4 shows the Cherokee, Wagoneer, and Comanche with idle jumper harness installed.

 

3.   Recheck the idle speed using a tachometer and verify that it is 950± 50 RPM

 

4.   Remove the tachometer.

 

        NOTE :     THE IDLE SPEED JUMPER HARNESS HAS THE SAME EFFECT ON VEHCILES EQUIPPED WITH OR WITHOUT AIR CONDITIONING. THE JUMPER HARNESS CAUSES AN INCREASE IN IDLE SPEED BY SENDING A STEP-UP SIGNAL TO THE ECU THAT SIMULATES FULL-TIME SIMULATES FULL TIME AIR CONDITIONING OPERATION. THE LOW IDLE SPEED JUMPER HARNESS SHOULD BE REMOVED FROM THE EEC HARNESS PRIOR TO TESTING THE VEHCILE WITH THE DRB II OR THE MS 1700 TESTER TO PREVENT INVALID TESTS.

 

These plug in to the ECU harness over by the relay center on the passenger side of the MJ or XJ.

[GrandComanche]

Will this work on a manual?

[eaglescout526]

57 minutes ago, GrandComanche said:

Will this work on a manual?

Yes. It will work with both transmissions. 

[eaglescout526]

Moved to tech.

[Rubikahn]

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