NO SPARK from coil

[rdnecks]

I have a 1988 Chevy Z71 K3500 1 ton. Engine is a 454 7.4L

My problem is this brackets that hold the alternator and power steering pump broke which in turn broke the bolts off in the block. I took the manifold off to tap out the broken bolts.

Had to take of the Distributor, Manifold, TBI unit off and unplug eletric wires.

Put back on Manifold, TBI unit and Distributor. Hook all electrical wires up and NO SPARK from the coil.

With having the bad luck of buying new parts from O'Rielly's and Autozone we have everything checked that can be check to make sure there good before we leave the store and we make sure and buy life time warrenty products now.

With No spark we replaced the ignition coil with a new coil that was tested at a alternator shop. Tested good. Still NO SPARK from coil.

Tested wires going into the coil from the battery. Getting 12 volts to the ignition coil.

Had ignition module tested at O'Reilly's and Autozone both said it was good but Autozone said sometimes there tests will test good and it still be bad so they replaced it with new one that they tested as good. STILL NO SPARK from coil.

Tested wires from iginition coil that plug into ignition module. Getting 12 Volts from coil to ignition module.

Tested pickup coil. Tests good.

Next we completely replaced Distributor assembly with new one. Includes pickup coil and ignition module. Still NO SPARK from coil.

Replaced computer with good one. Still NO SPARK from coil.

Rewired all wires from the computer to the ignition module. Still no spark from coil.

Replaced Rotor bug, Distributor cap, and plug wires. Still NO Spark from coil.

Checked all ground wires. They all seem to be good.

Checked Fuses all good.

Rotor bug is turning when engine is cranked.

Getting fuel.

I am at a total lose of what to do know. Any ideas anyone?

Thanks for everyones time.

[Fireplug]

It sounds like you have a ground problem or a loose wire

[rpreston]

Does your 88 have the oil pressure sensor behind the distributor at the back of the intake manifold? Been told that if the computer does not see the correct signal from the pressure sensor, it assumes no oil pressure and disables the ignition. I don't know for sure which years and engines this applies to, but you may want to check into it.

[Rbraczyk]

Did you reconnect the Negative battery ground to the intake manifold?

[rpreston]

Also, like above suggestion, double check the ground wire on the thermostat housing bolt. That's the ground for the ECM.

[rdnecks]

After digging and checking. We have found we have no power to the ECM.

We have power from the battery and starter into the ingition switch but no power from igition switch to the ECM. We also don't have power on the crank fuse and the panel light fuse in the fuse box. The Service Engine Soon light doesn't come on anymore and the Check Gauges light on the dash will only come on when you wiggle the key when you try and crank the engine. Also the temp gauge will go all the way up when the Check Gauges light comes on.

From the looks of the wiring all the wiring under the dash goes into the battery box on the fire wall inside the truck back out into the engine compartment around to the passenger side and back into the computer from there. Instead of routed under the dash to the ECM.

From this I am not sure if we are dealing with a bad igition switch, wiring under the dash or under the hood.

We are getting power to the igition switch. From the Chilton and Hayes manuals it shows the power to the ECM is a pink wire from the igition switch that has a 3A then turns into a purple and white wire. We are getting power on the pink wire from the iginition switch. Not sure if that pink wire goes into the battery box on the fire wall then turns into the purple and white wire.

We are trying to track. This one down. Thanks for everyone helps. Any ideas please let us know.

[allenz71]

I have the same problem with my 1992 Chevy Z71, and I tried everything you did... Did you ever end up fixing it... What did you do?

Allen

Originally Posted by rdnecks

I have a 1988 Chevy Z71 K3500 1 ton. Engine is a 454 7.4L

My problem is this brackets that hold the alternator and power steering pump broke which in turn broke the bolts off in the block. I took the manifold off to tap out the broken bolts.

Had to take of the Distributor, Manifold, TBI unit off and unplug eletric wires.

Put back on Manifold, TBI unit and Distributor. Hook all electrical wires up and NO SPARK from the coil.

With having the bad luck of buying new parts from O'Rielly's and Autozone we have everything checked that can be check to make sure there good before we leave the store and we make sure and buy life time warrenty products now.

With No spark we replaced the ignition coil with a new coil that was tested at a alternator shop. Tested good. Still NO SPARK from coil.

Tested wires going into the coil from the battery. Getting 12 volts to the ignition coil.

Had ignition module tested at O'Reilly's and Autozone both said it was good but Autozone said sometimes there tests will test good and it still be bad so they replaced it with new one that they tested as good. STILL NO SPARK from coil.

Tested wires from iginition coil that plug into ignition module. Getting 12 Volts from coil to ignition module.

Tested pickup coil. Tests good.

Next we completely replaced Distributor assembly with new one. Includes pickup coil and ignition module. Still NO SPARK from coil.

Replaced computer with good one. Still NO SPARK from coil.

Rewired all wires from the computer to the ignition module. Still no spark from coil.

Replaced Rotor bug, Distributor cap, and plug wires. Still NO Spark from coil.

Checked all ground wires. They all seem to be good.

Checked Fuses all good.

Rotor bug is turning when engine is cranked.

Getting fuel.

I am at a total lose of what to do know. Any ideas anyone?

Thanks for everyones time.

[Rs051802]

Have you tried using a meter and following the ignition wiring diagram from start to finish on your truck? You might try it, could save you some money. There is a fault somewere in the ignition. Do your gauges light up when you turn the key forward? Any rebuild manuel for an 88 will have electrical diagrams for this truck. I have a 95 and there is a white wire on the passenger side firewall that connects to the rear of the head. If this wire comes disconnected it will cause the truck to not fire. Good luck keep us posted on whats happening.