Fixing lazy PCM. New caps writeup.
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I kick this thread back up because it pertains to my question. I figured my PCM went bad. Ordered one from Rockauto, but I have to await delivery. While waiting on that I figured I would try this fix. My 95 5.2 board was a little different then OP's. So I guessed on polarity. When I plugged it in I heard the "pop". So would that be just the capacitors or would it also fry the whole board?
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Yes, the electrolytic capacitors must be properly installed. This reply shows the correct orientation for the capacitors.
Note that the PCB has a square pad for pin 1, the positive capacitor lead. The radial electrolytic capacitor has a stripe / arrow / minus sign for the negative capacitor lead.
When an improperly installed capacitor fails it could create a surge that damages other parts.
Note that the PCB has a square pad for pin 1, the positive capacitor lead. The radial electrolytic capacitor has a stripe / arrow / minus sign for the negative capacitor lead.
When an improperly installed capacitor fails it could create a surge that damages other parts.
Are the V8 Modules as bad about having problems as the 6cyl. .. As I've owned 2 more 6 cyl. Now I have a 3rd 6cyl 1995 .. All the 6cyl have had issues.
But I'VE Now bought a V8 1995 THAT'S BEEN SETING FOR ABOUT 5 YEARS I'M WORKING ON IT. It has 245,000 on it .But it seems to be rather nice. I've driven it several times . But only for maybe 2 or 3 minutes at a time. I'm thinking it must have some issues .. Or why was it setting ... V8 SEEMS TORUN & iDEAL FINE. & The lady said she had had the trans rebuilt ... Dealer for $3000.00 .. about 5000 mile before they quit driving it. She gave it to her son who ... Left it set while he went to the Army .. I'm not sure he came home.
But it doesn't have a front drive shaft in it. So I expect the Viscosity coupling is out. But I'm also wondering if it has a MODULE ISSUE ALSO .......
But I'VE Now bought a V8 1995 THAT'S BEEN SETING FOR ABOUT 5 YEARS I'M WORKING ON IT. It has 245,000 on it .But it seems to be rather nice. I've driven it several times . But only for maybe 2 or 3 minutes at a time. I'm thinking it must have some issues .. Or why was it setting ... V8 SEEMS TORUN & iDEAL FINE. & The lady said she had had the trans rebuilt ... Dealer for $3000.00 .. about 5000 mile before they quit driving it. She gave it to her son who ... Left it set while he went to the Army .. I'm not sure he came home.
But it doesn't have a front drive shaft in it. So I expect the Viscosity coupling is out. But I'm also wondering if it has a MODULE ISSUE ALSO .......
Tale of woe and now bliss
Bought a 2nd hand 1994 GC 5.2L 4WD a few years back for my daughter to use as a barn truck. She moved West and left it with me and I only drove it occasionally. It started running rough/rich. It would never throw a code. I tried various simple fixes, cleaned the throttle body and a new coil. Found the "12 things you can do" pinned thread and started working that. Didn't really help. I took it to a reputable mechanic who put in a new fuel pump, which seemed reasonable given the symptoms. Didn't really help.
A few months back as I was reaching a level of frustration, the transmission went out. I took it to a really good independent shop for a rebuilt transmission and also told them about the other symptoms. They put in the transmission and couldn't find the source of the other problems, although they put a new crankshaft position sensor while they had it apart. It got a little better for a little while. But it would act up, I would leave it with them and they couldn't get it to fail.
Finally, in the last couple of months it became almost undriveable. Same symptoms I read about here. Even more really, the interior display would reboot randomly and I would get 6 beeps. No codes. Finally, I did get a PCM code - the dreaded 53. I knew I would have to replace the PCM, so I decided to try this thread first. Lucky for me, my brother was DOD trained in component level electronic repair and circuit board construction. I showed him this thread and he said it sounded reasonable. I am in the computer industry and know all about the 1990s bad caps issue. I ordered the hardened caps from digi key and brother installed them. He said 40 watts was way too much and he also used something to wick out the solder. Anyway, 10 minutes later I had the new caps installed.
I reinstalled the PCM and drove around the block. The jeep immediately lost power, but it threw a code. This time it was 14 - Manifold Absolute Pressure sensor. Got out the multimeter and it was getting the 5V it was supposed to from the PCM. Got a new MAP sensor and installed it and the Jeep now runs like a champ! Thanks so much to this forum and the posters who showed the way with this problem.
Bought a 2nd hand 1994 GC 5.2L 4WD a few years back for my daughter to use as a barn truck. She moved West and left it with me and I only drove it occasionally. It started running rough/rich. It would never throw a code. I tried various simple fixes, cleaned the throttle body and a new coil. Found the "12 things you can do" pinned thread and started working that. Didn't really help. I took it to a reputable mechanic who put in a new fuel pump, which seemed reasonable given the symptoms. Didn't really help.
A few months back as I was reaching a level of frustration, the transmission went out. I took it to a really good independent shop for a rebuilt transmission and also told them about the other symptoms. They put in the transmission and couldn't find the source of the other problems, although they put a new crankshaft position sensor while they had it apart. It got a little better for a little while. But it would act up, I would leave it with them and they couldn't get it to fail.
Finally, in the last couple of months it became almost undriveable. Same symptoms I read about here. Even more really, the interior display would reboot randomly and I would get 6 beeps. No codes. Finally, I did get a PCM code - the dreaded 53. I knew I would have to replace the PCM, so I decided to try this thread first. Lucky for me, my brother was DOD trained in component level electronic repair and circuit board construction. I showed him this thread and he said it sounded reasonable. I am in the computer industry and know all about the 1990s bad caps issue. I ordered the hardened caps from digi key and brother installed them. He said 40 watts was way too much and he also used something to wick out the solder. Anyway, 10 minutes later I had the new caps installed.
I reinstalled the PCM and drove around the block. The jeep immediately lost power, but it threw a code. This time it was 14 - Manifold Absolute Pressure sensor. Got out the multimeter and it was getting the 5V it was supposed to from the PCM. Got a new MAP sensor and installed it and the Jeep now runs like a champ! Thanks so much to this forum and the posters who showed the way with this problem.
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This is an awesome thread and write-up. I have a 93 Grand that has been in the family, since inception. About 5 years ago there were reliability issues, so had get another car. I decided to keep it a s a spare car and only took it out on weekends. Did normal maintenance and then about 3 years ago I started with random engine loping, random stalls, hesitations and began reading this board and replacing with aftermarket parts (ips, cps, tps, cap, rotor, plugs, wires, even upgraded to 2 gauge electrical, etc) which always seem to fix the problem, but the issues always seemed to return at later time, so I would replace again and the problem went away again.
In the past 6 months I noticed the engine light would not come when turning the key to start. Without cranking I had to turn the ignition switch off to on 3 times and then the engine light would come on. Similar to getting the PCM codes. On third time engine light came on and when it went off I cranked the engine started. With this trick I never seem to hear the pump prime, was thinking fuel pump, but didn't want to spend the money or the time to install. Finally about a month ago the jeep died on the side of the road and couldn't get the thing started no matter. Did my trick, but engine light never came on. Jeep would crank, but never started. I had it towed home because I didn't want to spend any more money on the jeep and was planning of either parting out or selling the jeep for scrap.
I did one more last ditch effort to do a search on the jeep forum and found this thread. I saw many pcm articles related to connectors failing newer jeep zjs which could be re-soldered, but never saw this thread until now. I read the writeup and thought what do I have to loose. I ordered capacitors and soldering iron jeep from amazon. In the meantime I got the pcm out of the jeep. Cleanup and got the gel off as shown. Once the order showed I got to work soldering. Found getting the old ones out were a little trick because I had to balance the board while heating the capacitor on the soldered side while wiggling and tugging the capacitor from the other. Once I got them all out and cleanup up left over solder and installed and cleaned as in the writeup.
Once in stalled crossed my fingers, turned the key to start and engine light came on, and also heard the fuel pump prime. Engine light went out. I cranked and voila it started almost instantly. I let it run and was running smoother than ever. I shutdown after 10 minutes and tried to see if it would start on a warm start. Did the same test light and again started without hesitation. I was grinning ear to ear the rest of the day.
Again this was an excellent write-up.
In the past 6 months I noticed the engine light would not come when turning the key to start. Without cranking I had to turn the ignition switch off to on 3 times and then the engine light would come on. Similar to getting the PCM codes. On third time engine light came on and when it went off I cranked the engine started. With this trick I never seem to hear the pump prime, was thinking fuel pump, but didn't want to spend the money or the time to install. Finally about a month ago the jeep died on the side of the road and couldn't get the thing started no matter. Did my trick, but engine light never came on. Jeep would crank, but never started. I had it towed home because I didn't want to spend any more money on the jeep and was planning of either parting out or selling the jeep for scrap.
I did one more last ditch effort to do a search on the jeep forum and found this thread. I saw many pcm articles related to connectors failing newer jeep zjs which could be re-soldered, but never saw this thread until now. I read the writeup and thought what do I have to loose. I ordered capacitors and soldering iron jeep from amazon. In the meantime I got the pcm out of the jeep. Cleanup and got the gel off as shown. Once the order showed I got to work soldering. Found getting the old ones out were a little trick because I had to balance the board while heating the capacitor on the soldered side while wiggling and tugging the capacitor from the other. Once I got them all out and cleanup up left over solder and installed and cleaned as in the writeup.
Once in stalled crossed my fingers, turned the key to start and engine light came on, and also heard the fuel pump prime. Engine light went out. I cranked and voila it started almost instantly. I let it run and was running smoother than ever. I shutdown after 10 minutes and tried to see if it would start on a warm start. Did the same test light and again started without hesitation. I was grinning ear to ear the rest of the day.
Again this was an excellent write-up.
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By the way forgot to mention here are the parts I ordered.
12pcs Nichicon PL Radial Capacitor 220uf 35v 105C
https://www.amazon.com/gp/product/B06XGP82M1/ref=od_aui_detailpages00?ie=UTF8&psc=1
ANBES Soldering Iron Kit Electronics, 60W Adjustable Temperature Welding Tool, 5pcs Soldering Tips, Desoldering Pump, Soldering Iron Stand, Tweezers
https://www.amazon.com/gp/product/B06XZ31W3M/ref=od_aui_detailpages00?ie=UTF8&psc=1
12pcs Nichicon PL Radial Capacitor 220uf 35v 105C
https://www.amazon.com/gp/product/B06XGP82M1/ref=od_aui_detailpages00?ie=UTF8&psc=1
ANBES Soldering Iron Kit Electronics, 60W Adjustable Temperature Welding Tool, 5pcs Soldering Tips, Desoldering Pump, Soldering Iron Stand, Tweezers
https://www.amazon.com/gp/product/B06XZ31W3M/ref=od_aui_detailpages00?ie=UTF8&psc=1
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1 Posts
I am having lazy pcm issues too. This is how I currently start my 95 ZJ 5.2L Laredo:
- Turn the key to on
- wait for check engine light to come on (usually takes less than 15 seconds but can take minutes if really cold)
-> prior to the light coming on the auto shutdown relay rattles
- cel comes on and I hear the fuel pump
- count to 15 slowly
- starts right up
I avoid all this ifI drove for more than 10-15 minutes. I will order the capacitors and try this fix then report back.
Thanks!!!
- Turn the key to on
- wait for check engine light to come on (usually takes less than 15 seconds but can take minutes if really cold)
-> prior to the light coming on the auto shutdown relay rattles
- cel comes on and I hear the fuel pump
- count to 15 slowly
- starts right up
I avoid all this ifI drove for more than 10-15 minutes. I will order the capacitors and try this fix then report back.
Thanks!!!
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