Problems starting 93 Grand Cherokee in cold weather

[mktgpro]

My 93 GCL (4.0 with 250,000 miles) will not start in cold weather until the check engine light comes on, and this requires me to turn the key just before the crank position and waiting...sometimes for 10 minutes. Have replaced all the sensors commonly associated with this problem as well as the starter. My mechanic checked fuel pressure and said it was fine. He also checked to see if this were a transmission issue. Just before the check engine light comes on, there is a clicking sound from the passenger side. Any suggestions or guidance will be appreciated.

Overall, this has been a great vehicle. After reading other posts, I feel lucky. Replaced the transmission, alternator and radiator at 200,000 miles, but no other major issues since buying it new.

[zerotohero192]

now im in no way an expert, but i took my jeep to a mechanic and they said fuel pump. i took it to a garage that my girlfriends dad has been goin to for almost 10 years and they said it was the computer, which makes more sense because it explains a couple of other problems i've been having. so go someplace that checks computers, maybe to rule it out?

[bringselpup]

I would say PCM

Look up posts from me from a little over a year ago. You can proof your pump to be sure.

[tallkid_87]

i aswell am have the same problem to the tee.

[mktgpro]

A different garage that claims lots of experience with computers has tested the computer and the mechanic says it is OK. He thinks the problem is with the alarm system switch in the driver's side door and is replacing the switch. I've been travelling so don't have the vehicle back yet, but he told me on the phone that this solved the problem. Will get back with you and confirm details from his work order next week.

[bringselpup]

No problem believing that.

[dkmac93]

I have had this problem as well and by checking the voltage at the vehicle speed sensor( rear of tranny) with key on, before and after the check engine light comes on.
Should be approx 8-9 volts with key on. This voltage is for the VSS,CPS & Cam Position Sensor. All other sensors use the 5volt supply from the PCM,(TPS,MAP.etc.).
Found mine to be 11.5 volts, when first turned on and cold then slowly drops to 9.5 volts before the check engine light comes on(15 min in the cold). this is the 8volt regulator in the PCM acting up in colder weather.
I fixed mine by opening the PCM case and carefully digging out the soft foam to get the circuit board out of the case,(not easy), then I replaced the three electrolitic capacitors on the board for the power,5 volt reg & 8 volt reg. Now 8volt supply is approx 9 volts at vehicle speed sensor warm or cold and all ok.
Would not recommend this method unless you know something of electronics & computers.
Easier to get a replacement PCM off Ebay or parts supplier,just be sure the part codes on the PCM match what your buying.

Mine is a 93 5.2l grand with 261000Km on it.

[mktgpro]

Turns out it was the ECM after all. The mechanics thought the door switch had solved the problem, but after leaving the vehicle outside over a cold night, they pulled an ECM out of another Jeep and put into mine. Then it started right up. With a new ECM from Advance Auto Parts ($278), it now starts perfectly whether the temp is cold or not. I have noticed that gas mileage and power seems much improved with all the new sensors, so I guess that was a good investment, too. While I had the mechanic working on the left front door switch, I also had him install a new regulator for the back left door window, which was off its track and had not worked for some time. Cost for both doors, including labor, was about $225. Guess, I'll now try to get another 100K miles out of it. Thanks to all for your advice.