After a bit of googling I agree t is likely NOT the vehicle theft system preventing the fuel pressure, as apparently the VTSS will disable starting by the pcm trimming down the pulse width to the injectors after runniing for 2 secs, , not by cutting off the fuel pump.
After a bit of googling I agree t is likely NOT the vehicle theft system preventing the fuel pressure, as apparently the VTSS will disable starting by the pcm trimming down the pulse width to the injectors after runniing for 2 secs, , not by cutting off the fuel pump.
The OP has a '93 ZJ, the first generation ZJ.
The first generation ZJ vehicles do NOT have the Vehicle Theft Security System, VTSS. The first generation ZJ vehicles can have the optional Vehicle Theft Alarm, VTA, module.
The second generation ZJ vehicles are the ones w/ the VTSS.
Please provide a link showing how the VTSS is applicable to the OP problems.
Here is a decent article on the CCD bus that is used for communication between the VTA and the PCM.
Here is some interesting information from that article.
Bus Failure
The CCD data bus can be monitored using the DRBIII scan tool.
However, it is possible for the data bus to pass all tests since the voltage parameters will be in “range“ and false signals are being sent.
There are essentially 12 “hard failures“ that can occur with the CCD data bus:
Bus Shorted to Battery
Bus Shorted to 5 Volts
Bus Shorted to Ground
Bus (+) Shorted to Bus (–)
Bus (–) and Bus (+) Open
Bus (+) Open
Bus (–) Open
No Bus Bias
Bus Bias Level Too High
Bus Bias Level Too Low
No Bus Termination
Not Receiving Bus Messages Correctly
A multimeter is a useful tool to diagnose these fault conditions.
A computer w/ a serial interface port and appropriate hardware could be used as a "sniffer" to monitor the data communications on the CCD bus, using information in the linked article.
ok so while delivering pizza in my truck last night all i was thinking about was my jeep racking my brain for something i have missed. Two things came to mind maybe totally unrelated but may help point me in a direction as well. 1 my jeep has the EVIC that has all the sensor info on it that shows the time and date. every few days over the past month it will randomly do one of two things a) not come on at all until the next time you start the ZJ or b) just randomly act like it has lost power (flashing clock display). this has never been a big deal as the radio has a clock and i am fairly on top of all the fluids and such. it is currently flashing so i need to set it to see if a sensor is tripped or something stupid! the only other thing that i have had randomly happen is the gas gauge will just go to empty and turn on the low light and stay there now it has only done that two times but both were over the course of a couple days long each.
now being it was parked so long the mice moved in as it was a nice home for them i have pulled a lot of nest material out of my vents but i had been planning to take the dash down even more to get some more out as i still have a few vents not blowing like they should. Being i know i seem to have a short/bad connection on the EVIC I figure i will tear into the dash and look for possible wires that might be bare and or broken there first but i wanted to get some input on that idea as looks like this weekend i will get some time to get into it a bit.
The described VIC symptoms are common. The repair for that problem is to disassemble the VIC and touch up the solder joints. That repair didn't work on mine, so I swapped out the VIC.
This reply shows the internal circuit boards inside the VIC.
Getting closer! ok so today I started back at the beginning being i had daylight on my side so in a work through of all my fuses i found one blown!
in this picture my fuse with the issue is labeled in the FSM as number 6 it is the small 15 amp blue fuse that on the PDC map says Trans/ECU i was jumping for joy when i saw this! So i had one spare hoped it in went over turned the key and bam check engine light came on! in my excitement i went ahead and cranked it on over to start it knowing i had fixed my issue and still no start. So i tried to remember if i had noticed the pump run or relays click and couldn't remember them at all so turned the key back to on and no chk engine light once again so went to look at the fuse in question and it was blown again. Now that i am out of 15s i am going to dig into the wiring diagram and see if i can figure out where the power is coming from then where it goes and trace that looking for a short that might be killing this fuse. suggestions? one thing i do want to try is to replace the fuse then see if it blows only on crank or if it is a blow on just an on situation. will report back ASAP.
oh and one more thing just making an assumption here but being i have the 46RH do i need to look at my trans for anything? It kinda feels like i might be replacing my caps still yet!
Getting closer! ok so today I started back at the beginning being i had daylight on my side so in a work through of all my fuses i found one blown!
in this picture my fuse with the issue is labeled in the FSM as number 6 it is the small 15 amp blue fuse that on the PDC map says Trans/ECU i was jumping for joy when i saw this!
The PDC Fuse F6 15A provides power to the coils on both the Fuel Pump Relay and the Automatic Shutdown Relay, plus lots of other stuff. It also powers the: Data Link Connector #1 (near the PCM); the Exhaust Gas Recirculation Solenoid; the Overdrive and EMCC Solenoid; the Evap/ Purge Solenoid and is an input to the PCM labeled Ignition Start / Run on pin 9.
My guess is one of those places is a dead short, causing the fuse to blow.
Use a multimeter to measure the resistance to ground at the fuse location, then calculate the current using Ohm's law, I=-V/R.
Start unplugging each of those loads until the resistance becomes good to locate the problem.
Also measure the coil resistance for each load to ensure those are also not the problem.
So i ran to AutoZone to grab some fuses decided on the 25 pack in stead of the multi that only had one in it. Threw a new fuse and wanted to see if it was a on crank or a on switch blow and went to on light came on i went out checked fuse removed fuse put it back in with switch on and then put it back in relays cycled and i went in and started the jeep right up! so i figured complete fluke and turned it off then switch back to on and light still working so it fired right back up. So is it possible that the 20+ year old fuses i had and blew were just weak? as she seems completely fine and the only thing i have changed?
