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Meister Tech
Meister Tech, Jeep Master Technician
Category: Jeep
Satisfied Customers: 422
Experience:  Factory Certified Jeep Master Technician Gold Level
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93 grand cherokee: ASD and fuel pump relay..trans..control module

Resolved Question:

93 grand cherokee , ASD and fuel pump relay will not trip. it turns over in P and N but no fire or fuel .I think its something to do with trans control module or alarm system. thanks Mark.
Submitted: 7 years ago.
Category: Jeep
Expert:  Meister Tech replied 7 years ago.
I have Factory Master Gold certification with Jeep

If all the electrical inputs wires and grounds to the relays are good, then it is most likely that your crankshaft position sensor is the most probable cause. When the alarm system is active on this vehicle, you will at least get the engine to start up and then it will die out.

REMEMBER, we don't get paid unless you hit the *ACCEPT* key.

For Educational Purposes Only. Complies with U.S.C. Title 17 Chapter 1 section 107.
Customer: replied 7 years ago.
I have no continuity on the negative side of the relay to ground, is this a bad ground? and where is it? the wiring diagram shows it leads to the trans control module. Would the CPS affect this?
Expert:  Meister Tech replied 7 years ago.
-Could you explain your situation a little more?

Which relay exactly?

And which terminal on the relay are you regarding. There is a common ground and then there is the control side which is on terminal 85 usually. and terminal 86 should be a constant B+, then 30 is a constant B+ and 87 is the out put to the components and should be 12volts when the relay is activated.

If you have a fused jumper wire, you could momentarily jump terminals 30 and 87 and see if the car starts.

Note this is at your discretion.

Customer: replied 7 years ago.
I have jump 30 and 87 to fuel and ASD relay, the fuel pump comes on and have good pressure and i get constant B+ to coil. but timing light shows no fire to plugs.checked cap , rotor and wires is good.and new coil. if all the sensors are good, would it run by doing this? 86 is B+ with ingition switch on. 85 no ground no reading at all dead. cleaned ground wires to body by battery still no good. hook up batter lights flash no horn, turn key left lights off no horn. turn on ingition seconds later security light on dash comes on.well thats where i am thanks mark.
Expert:  Meister Tech replied 7 years ago.
The security light flashing is an issue that may be the root cause. You need to disable the alarm system by remote or cycling the key in the door lock cylinder a couple of times. Let me know how it goes. The actuating of the coil occurs from the engine controller making and breaking a ground to the coil. So I think it is the alarm system causing this.
Customer: replied 7 years ago.
cycled key stoped lights from flashing but a minute later the security light comes on dash.tried grounding VIO/YEL wire in door, stoped flashing light but minute later secuity light on dash comes on solid. still have same problem relay 85 dead. run jumper from 85 to B- get fuel and B+ to coil but no fire to plugs. tried removing alarm modules under glove box this stoped flashing lights and dash securit light. still 85 dead no fire. replaced crank position sensor. no good. yes distributor shaft turning.running out of ideas! its a vendetta ,me or the jeep! mark.
Expert:  Meister Tech replied 7 years ago.
With a factory style scan tool such as the Snap On - Brick you would be able to-verify that the alarm is activated in Fuel Kill mode. You need to see if you have an rpm output from the engine controller on the scan tool.

Do you have a scan tool?
Customer: replied 7 years ago.
no scan tool , i am going to check all the pin wires for ECU to each connection. if all wires are good i think the ECU is bad, with alarm in or out or disabled the problem remains the same. 85 dead and no signal to fire from ECU. i have found no severed wires or burnt wires. if the 85 leads just to the ECU then it must be the problem. what do you think? mark.
Expert:  Meister Tech replied 7 years ago.
Pin 85 or 25 on the power distribution center is a Pink wire and yes it is controlled by the PCM. This control is released if the alarm is deactivated. You need have someone with a factory scan tool verify that "Fuel Kill mode is deactivated. This must be seen with the scan tool. Even if you disconnect the alarm module, you are not literally removing it from the system, because the Pcm needs to see a disarmed signal to allow the engine to start.

It can be the PCM, but I never saw this happen. This does not mean it is not possible. I would personally pay for someone to verify what I stated above. A pcm is very expensive and usually not a returnable part.

REMEMBER, we don

Edited by Meister Tech on 7/29/2010 at 12:06 AM EST
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