My 99 jeep grand cherokee was t-boned at 10 miles per hr now it won"t start,is it a ignition fuse,or damaged ecm ?

Sounds like you need to perform a relearn on the anti theft system, it's not recognizing the key if this happens with the key inserted. Might want to look online for a reset procedure for Jeep. GM has you keeping the key in the ignition in the on position for 10 minutes.

When you say it loses power, do you mean electrical power or engine power ?
You would need to look at the fuse boxes for a loss of electrical power, and use a scanner or code reader to check the computer for trouble codes for a loss of engine power.

I would make sure you have voltage to the coil. Could be a fuse or relay problem. Is the check engine light on when you turn the key on ?

change the wires that go to the starter i had the same problem fixed now with no problems

Hope this helps:- Factory Disarm Purple/Yellow (-) Driver's Kick Panel Black Connector at ECM -slice into this wire, & wire it to ground, this disables the alarm.
Cavity/Fuse Diagram (1996 Grand Cherokee, passenger side kick plate to find, Owner's Manual pgs 205-206): 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Row 1: 1-6 (left to right) Row 2: 7-12 Row 3: 13-18 Row 4: 19-22
1996 Jeep Grand Cherokee Fuse Panel (Passenger Side kick panel) Reply

CAVITY FUSE DESCRIPTION 1 -10 amp (RED) Radio 2 -15 amp (Lt Blue) Cigarette Lighter 3 -10 amp (RED) Rear Washer Switch, Body Controller 4 -10 amp (RED) Airbag 5 -10 amp (RED) Lamp Out Module, Overdrive Switch, OBD II 6 -15 amp (Lt Blue) Vehicle Information Center/Graphic Display Module Park & Side Lamps, Overhead Console Lighted Visor, Automatic Dimming Mirror 7 -20 amp (Yellow) Body Amp, Cluster, Body Controller 8 -20 amp (Yellow) Rear Wiper Motor, Flipper Glass Solenoid, Cargo Lamp, Trailer Tow 9 -15 amp (Lt Blue) Brake Switch 10- 10 amp (RED) Rear Window Defroster 11 -10 amp (RED) ABS Module 12 -10 amp (RED) Heater-Ventilation-A/C Control & Recirculation Motor 13 -15 amp (Lt Blue) Hazard Switch, Turn Signal Switch 14 -15 amp (Lt Blue) Spare 15 -15 amp (Lt Blue) Spare 16 -10 amp (RED) Right & Left Courtesy Lamp, Glove Box Lamp, Halo Lamp Cargo Lamp, Underhood Lamp, Dome/Read Lamp Right & Left Visor, Automatic Dimming Mirror 17 -15 amp (Lt Blue) Radio Illumination, Tail Lamp, Graphic Display Module, Park & Side Lamps, Headlamp Switch, Body Controller 18 -20 amp (Yellow) Spare 19 -15 amp (Lt Blue) Passing Light 20 -15 amp (Lt Blue) Radio, Heater-Ventilation-A/C, Vehicle Information Center 21 -15 amp (Lt Blue) Power Outlet 22 -10 amp (Blue) Airbag Module -------------------------------------------------------------------------------------
1996 Jeep Grand Cherokee Alarm, Remote Starter, Keyless Entry Wiring Information Constant 12V+ Pink/Black Ignition Switch Harness Starter Yellow Ignition Switch Harness Ignition Dark Blue/Gray Ignition Switch Harness Ignition 2 Red/Black Ignition Switch Harness (for AC) Accessory Black/Orange Ignition Switch Harness Tach Gray/White Coil Brake Switch White/Tan Brake Switch Trunk Pin n/a Works with Dome Light Parking Lights Blue/Red (+) Left of Steering Column or Light Switch Head Lamp Tan/Black Light Switch Factory Disarm Purple/Yellow (-) Driver's Kick Panel Black Connector at ECM -slice into this wire, & wire it to ground, this disables the alarm. Door Trigger Yellow (-) Driver's Kick Panel see notes Door Lock 5/Wire in Driver's Inside Driver's Door Orange/Purple Lock Pink/Black Unlock Door Unlock and Passenger's Doors Inside Passenger's Door Black/White L Pink/Black Unlock Horn Wire Gray/Orange (-) Steering Column Windows Up LF=Light Blue, RF=Brown/White, LR=Blue/White, RR=Gray/Black Doors Windows Down LF=White, RF=Purple/White, LR=Red/Black, RR=Green/White
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Your ecm is going bad. If you haven't noticed yet, the vehicle will only start once the check engine light comes on, on the dash. That's the ecm finally sending power to the relays that feed the fuel pump and ignition systems. If you're mechanically and electrically handy you can remove the ecm, disassemble it and replace the three power capacitors inside. If not, just have the ecm checked and replaced.

similar problem with mine. disconnect battery for 45 min and better=
reconnect battery 1 hr later better/causes car computer to reset

First test the coil, Make sure you have power to it? If you do? Inspect the cap and rotor button for damage. If that all checks out? replace crank sensor

could be worn. try putting a can of stp transmission conditioner in. may solve problem and cheaper than a rebuild

base on the year jeep chect with your dealer some of thes features as a problem that realated to your vehicle ecu