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Jerry, Master Mechanic
Category: Jeep
Satisfied Customers: 17220
Experience:  ASE Master...30+ years...Shop owner..engine builder..collision structural repair
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93 jeep grand cherokee: a problem with the ignition coil..1500 miles

Resolved Question:

I have a 93 jeep grand cherekee with 235000 miles and a steight six. I have a problem with the ignition coil they only last about 1500 miles then I have to replace it. Have bought threw a few different places but always the same result. coil gets hot and wont run let it cool for a few hours and it well start but only run for a few miles before getting hot agin when I replace it its good for anouther 1500 please help
Submitted: 9 years ago.
Category: Jeep
Expert:  Jerry replied 9 years ago.

Hello and welcome to Just, Super mechanic here. About your vehicle.

Before you replace the coil again. I found a campaign on it. Let me see if I can copy it for you.


High ignition coil operating temperatures, combined with high ambient temperatures, can result in coil failure and cause poor engine performance, hard starting or a no start condition. To correct this condition, the coil must be replaced with a low resistance coil and an external resistor harness.

Important: Some of the involved vehicles may still be in dealer stock. Be sure to complete the service on these vehicles before retail delivery.


Details of this service action are explained in the following sections.

Service Procedure Videotape

No videotape of the service procedure for this notification will be provided.



Important: A quantity of parts will be distributed initially and billed to all involved dealers. This quantity will cover a portion of the total vehicles involved. Additional parts will be supplied as indicated in the Special Parts Supply Message with this notification letter.


Each involved dealer, to whom vehicles in the notification were invoiced (or the current dealer at the same street address), will receive enough Ignition Coil Packages, PN C3905840, to service 25% of those vehicles (minimum of 5 and maximum of 20 packages).

Each uninvolved dealer, will receive 5 parts packages to service vehicles upon request.

Each parts package contains the following components:

Quantity Description 1 Ignition Coil 1 Jumper Harness Package 1 Instruction Sheet


Owner Notification and Service Scheduling

All involved vehicle owners known to Chrysler are being notified of the service requirement by first class mail. They are requested to schedule appointments for the service with their dealers at the earliest possible date. A copy of the owner notification letter is included.

Enclosed with each owner notification is an Owner Notification Form. The involved vehicle and notification are identified on the form for owner or dealer reference as needed.

Service Procedure

1.The new coil and jumper harness may have already been installed through Technical Service Bulletin (TSB) 08-35-93. Inspect the primary coil wiring. If a jumper harness is present, the vehicle has already been repaired and no further action is necessary (Figure 1). The jumper harness can be identified by a rubber boot on the coil connector and a pink wire covered by a mesh convolute. The jumper harness should be looped and secured to the battery harness. All vehicles without this jumper harness must have the coil replaced and the jumper harness installed. Proceed to Section B.


B.Replace Ignition Coil:



With the ignition key in the OFF position, disconnect the negative battery cable.

To ensure customer satisfaction, remember to record all radio settings before disconnecting the battery and to reset the electronic memory when you have completed the service procedure.


2.Disconnect the secondary and primary wiring from the ignition coil.


3.Remove coil assembly from bracket. Discard the ignition coil.


4.Install the provided ignition coil on bracket. Connect the secondary coil wire.


5.Remove the primary coil wires from the wiring insulator on the engine harness.


The terminal locking tab must be depressed using a paper clip or small screwdriver (from the terminal end) while pulling back on the wire.

Install insulator, wedge and seal supplied in the jumper harness package onto the engine primary coil wires


Make sure proper coil polarity is maintained. Insert the gray/white (B-) wire into the insulator cavity that will connect to the gray/white wire on the supplied jumper harness. Insert the dark green/black (B+) wire into the insulator cavity that will connect to the pink resistor wire on the supplied jumper harness.


7.Connect the supplied jumper harness to the ignition coil and primary coil wiring (on engine harness). Loop the jumper harness toward the battery and secure it to the battery harness in three locations using the attached tie straps.
Make sure jumper harness is away from all sharp edges and moving parts.


8.Connect the negative battery cable.
Customer: replied 9 years ago.
good info I checked the wire harness and I do have the updated one but not the right coil called the dealer and got the right part number but when I went to napa to get it the coil has round termenals and my harness has spade termenals
Expert:  Jerry replied 9 years ago.

Some things are better to get from the manufacturer. That may be one of them.

I noticed that Autozone offers both kinds but you never know if they are the uupdated ones. That may be why your going through them so often.

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