I have a 95 Transam that won't start. My son replaced the radiator and water pump then three days later it just wouldn't start. It tries to crank but doesn't. Our mechanic replaced the distributor, cap, and rotor. He installed a new brain box. He took it to GM and they scoped it and said the security module needed to be replaced. He replaced that and nothing. Then he replaced the VATS. He showed me that there is intermittent fuel injection pulse and he doesn't know why and it is generating code 18. I did some research and found that code 18 says:
crank signal circuit
ECM fault injector circuit (vin P-5.7L)

He's checked wires and grounding. The strange thing is that if he unhooks the new distributor and rotates it by hand it starts. Any suggestions?? The PurplePig is sucking the money out of us at a rapid rate!

 

try a crank sensor

 

I'm not all that familiar with the LT1's....but I didn't think they had a distributor, cap, and rotor...I thought GM replaced all that with their wonderful optispark idea....

I believe on LT1's, the optispark is right below the waterpump, so if anything dripped on it while the waterpump was being replaced, the optispark could have turned into opticrap. If that hasn't been replaced, that might be a place to look...if that's what your mechanic is saying is the distributor, cap, and rotor...then I'm not sure...

 

I have owned 5 LT1 cars. Still own 1. I have never gotten any codes but the one time when my car wouldnt start and i checked everything else it turned out to be the ignition switch. The ignition switch is located in the steering column and is a real bitch to get out. It cost like $35-40 from a local dealership. Go to Camaroz28.com or the LT1 section on this board. Good Luck. Also did he replace the coil and made sure when the waterpump was put on it didnt drip onto the optispark?

 

code 18 Injector driver circuit voltage to PCM was wrong for 4 seconds.try replacing the fuses and checking the wiring for the injectors.the injectors are powered with 12 volts through fuses in the fuse panel and the PCM grounds the injectors to fire them.

 

rotates it by hand? explain that?????

 

Thank you all very much for your insight! I am the Mom of the PurplePig and am learning more about cars that I ever thought I would! The crank sensor and optispark have been checked already. The mechanic is going to replace the ingition and coil Monday. My husband said he thinks the optispark has already been checked, but red flags were raised when you said that the optispark can turn into opticrap if it got wet changing the water pump. My 17 year old, who drives the car, changed the radiator and water pump in autotech at school. I suspect most of his work was unsupervised.

In answer to YoMommasTa, I have no clue what he means by rotating the distrubuter by hand! Great choice of nick names though!

Thank you all,

PurplePig

 

there is no distributor, cap, or rotor on an LT1 car. ur code is telling u the crank sensor is pretty much dead. and im not sure if the LT1 had a cam sensor as a backup just like the LS1. replace the crank sensor and all will be fine IF the optispark wasnt completely destroyed. and i dont know how hes turning the "distributor" by hand. can u explain a little more?

if ur mechanic is telling u he replaced a distributor, cap, and rotor, id find a new mechanic. hes smoking something fierce.

 

I have the same problem....with my trans am 1995, I did replace the starter (it was damaged, I assumed that it was the reason that car didn't start), but it continues doesn't start, I have a crack, but the engine doesn't start. Please any suggestions?