crank/no start

[fordfan1000]

I've got a 98 Ram which cranks with good speed but will not start.I can't communicate with the PCM with my scan tool,have no spark and no fuel pressure.I checked the PCM grounds and replaced 2 of them,checked for voltage to the coil with the key on /engine off and get about .32 volts which goes up to 1.2 when cranking.I got almost exactly the same readings at my MAP,cam and crank sensors.I checked the wiring for high resistance from all the wires to the PCM and I get about .7 Ohms.The voltage into the PCM is over 12.I believe it is the PCM but would value more opinions,maybe someone has came across the same situation?

[jdl]

I didn't see an engine size? I don't know if this will help or not.

Pin 16 at the DLC should always have power. pin 4 always has chassis ground. pin 5 should be signal ground. I don't have a good enough wiring diagram to trace those circuits.

My info says to backprobe those circuits from the back of the connector. Do a voltage drop test on pins 4 and 5 with the circuit loaded. Load it by plugging in the scanner. Should be a 100mv or less. Do the pins in the DLC look ok?

Do you have good B+ going to the coil and injectors, with engine cranking? That voltage comes from the ASD relay.

Have you checked the ref voltage at the pcm for the crank,cam, map sensor, they use the same circuit?

You may be correct about the pcm, I can't tell, from here. Did you try tapping on the pcm while a helper cranks the engine?

[fordfan1000]

Thanks for the help,I'll try those tips out tomorrow.

[wafrederick]

If it is the PCM,you have to take it to the dealer.The new PCM has to be programed and the vin burned in with Chrysler's factory scan tool DRB III and there is a core charge on the old PCM.The Vetronix scan tool,Mastertech will program the PCM and the vin burned in also.You can get an used PCM from an auto slavage yard and it is probally 1998 only if looked up in a parts interchange book called a hollander.Chrysler PCMs can only be programed once and they done after that.

[Jimmy96er]

Originally Posted by wafrederick

If it is the PCM,you have to take it to the dealer.The new PCM has to be programed and the vin burned in with Chrysler's factory scan tool DRB III and there is a core charge on the old PCM.The Vetronix scan tool,Mastertech will program the PCM and the vin burned in also.You can get an used PCM from an auto slavage yard and it is probally 1998 only if looked up in a parts interchange book called a hollander.Chrysler PCMs can only be programed once and they done after that.

Similar experience with my truck after we did an engine rebuild. No spark, no fuel...etc. turns out it was the PCM. We replaced it with a used one of the same year and now it works but it has intermittent ABS and parking break lights that go on every so often. No engine codes seen on my OBDII scanner. Its about an hour charge in the dealership to flash the computer, and thanks wafrederick for the info stated above -

I just got my truck back today and Im really excited.

[fordfan1000]

Well,here we are months later,finally talked the guy into buying a PCM and the truck fired right up.