Topic: ECU Problems

[95jeeper]

Well my jeep is only running on 3 cylinders. Got the check engine light checked and the mechanic told me the number 1 injector is miscommunicating  with the computer. So i got a new injector and she still runs on 3. So do i need to replace the computer or is there a way to get it reprogramed or reset it some how?

[sharpxmen]

Well my jeep is only running on 3 cylinders. Got the check engine light checked and the mechanic told me the number 1 injector is miscommunicating  with the computer. So i got a new injector and she still runs on 3. So do i need to replace the computer or is there a way to get it reprogramed or reset it some how?

check to see if you get a signal on the connector (use a needle type multimeter or a low power light bulb). there is no way to reprogram it - it's either wiring, the injector or the PCM component that controls the opening and closing that specific injector (since the other 3 are working).

if you do get a signal then it's the injector or the spark for that cylinder.

[95jeeper]

i tested the connector with a light and its getting power. so i put the #2 plug on the #1 injector and it started working, Put the #1 on #2 still nothing. SO the #1 injector is fine. Whats going on, is it not getting data but getting power, what can i do to fix this

[sharpxmen]

i tested the connector with a light and its getting power. so i put the #2 plug on the #1 injector and it started working, Put the #1 on #2 still nothing. SO the #1 injector is fine. Whats going on, is it not getting data but getting power, what can i do to fix this

check that is getting ground too, the + is from ASD and always "on" when the engine is running, the PCM provides ground intermittently so the injector is opening and closing as per engine load - use a light bulb or needle multimeter between the 2 contacts on the injector connector (don't use an external ground). if that turns out to be faulty (no indication of signal on the connector) then verify the ground wire that goes to the PCM (pin 16 at the PCM for injector #1, the wire is white with a dark blue line on it) - take the connector out and check connectivity that way, while you're at it make sure the pin makes good contact in the PCM (inspect it to insure there is no oxidation). if all that turns out good you might be in for a replacement PCM. 

[95jeeper]

Finally got some time to check it out. Tested the connection between the two contacts at the injector and no signal. Tested number 2 injector and light flashed on and off. Next i removed the plug from the pcm and inspected the pins and plug.... they looked almost brand new. So am i lookin at a replacement pcm. Refurbed, new, what should i get and where to get it.

[Jeffy]

Finally got some time to check it out. Tested the connection between the two contacts at the injector and no signal. Tested number 2 injector and light flashed on and off. Next i removed the plug from the pcm and inspected the pins and plug.... they looked almost brand new. So am i lookin at a replacement pcm. Refurbed, new, what should i get and where to get it.

Did you check for connectivity between the PCM plug and the injector plug?

[sharpxmen]

Did you check for connectivity between the PCM plug and the injector plug?

x3 (look at my prev post for the PCM pin#)

check that is getting ground too, the + is from ASD and always "on" when the engine is running, the PCM provides ground intermittently so the injector is opening and closing as per engine load - use a light bulb or needle multimeter between the 2 contacts on the injector connector (don't use an external ground). if that turns out to be faulty (no indication of signal on the connector) then verify the ground wire that goes to the PCM (pin 16 at the PCM for injector #1, the wire is white with a dark blue line on it) - take the connector out and check connectivity that way, while you're at it make sure the pin makes good contact in the PCM (inspect it to insure there is no oxidation). if all that turns out good you might be in for a replacement PCM. 

[95jeeper]

Alright finally got around to workin on her again, Checked the connectivity between the pcm plug and the injector, everything is good, Tested both the ground and pos. so am i look at a new pcm? Where can i find one that might actually work?

[jfrabat]

Alright finally got around to workin on her again, Checked the connectivity between the pcm plug and the injector, everything is good, Tested both the ground and pos. so am i look at a new pcm? Where can i find one that might actually work?

I bought one for mine from eBay for about $40...  Has worked fine so far (over 1 year).