Maybe ECM Problems on my C4 ??
Thread Starter
Heel & Toe
Joined: Mar 2001
Posts: 17
Likes: 0
From: Germany
Maybe ECM Problems on my C4 ??
Hello everybody,
Round about 5 min. after starting the engine of my 90th vette, when it was cold, a lot of the relays on the LH side of the steering column (underneath the dash board) and in the engine compartment starts clicking.
By every click the "Service Engine Soon" light flashes and the engine starts to have cutouts until it dies.
If I try to start the engine again it dosn't start and the relay are clicking, the "Service Engine Soon" light flashes and the cooling fan is running.
The ECM seams to switch to the diagnostic mode.:confused:
But the only trouble code that is shown is code 12.
Does anybody know something about that problem?
Thanks in advance.
Round about 5 min. after starting the engine of my 90th vette, when it was cold, a lot of the relays on the LH side of the steering column (underneath the dash board) and in the engine compartment starts clicking.
By every click the "Service Engine Soon" light flashes and the engine starts to have cutouts until it dies.
If I try to start the engine again it dosn't start and the relay are clicking, the "Service Engine Soon" light flashes and the cooling fan is running.
The ECM seams to switch to the diagnostic mode.:confused:
But the only trouble code that is shown is code 12.
Does anybody know something about that problem?
Thanks in advance.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Maybe ECM Problems on my C4 ?? (Karsten90)
I think your ECM is heating up and losing power. Do this to try to verify that.
Start up your car and disconnect the set-timing connector. It should set a code 42. Now turn the car off and reconnect it. Your car should run fine, but it should still have code 42 in memory.
Run the car until it messes up. Check the codes. If your ECM only flashes code 12 and not code 12 AND code 42, then your ECM is losing power. Either due to a bad ground, bad positive feed, bad connection at the MEMCAL (which is the chip seated in the ECM) or something going wrong internally in the ECM.
Good luck, -Matt-
Start up your car and disconnect the set-timing connector. It should set a code 42. Now turn the car off and reconnect it. Your car should run fine, but it should still have code 42 in memory.
Run the car until it messes up. Check the codes. If your ECM only flashes code 12 and not code 12 AND code 42, then your ECM is losing power. Either due to a bad ground, bad positive feed, bad connection at the MEMCAL (which is the chip seated in the ECM) or something going wrong internally in the ECM.
Good luck, -Matt-
Thread Starter
Heel & Toe
Joined: Mar 2001
Posts: 17
Likes: 0
From: Germany
Re: Maybe ECM Problems on my C4 ?? (HighHopes85)
thanks Matt, I will try.
But can this be te cause why the ECM switches automatically to the diagnostic mode?
I disconnected the black/white wire that is responsible for switching to the diagnostic mode, but it wasthe same like before.
But can this be te cause why the ECM switches automatically to the diagnostic mode?
I disconnected the black/white wire that is responsible for switching to the diagnostic mode, but it wasthe same like before.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Maybe ECM Problems on my C4 ?? (Karsten90)
If the fan kicks on and the check engine light does not flash (just stays lit), you are not in diagnostic mode--you are in Limp-home mode.
The black/white wire has nothing to do with diagnostic mode. That wire (if we are talking about the one by the brake booster) controls spark advance and if you disconnect it, you just don't get spark advance at the distributor. That is different from diagnostic mode.
The only reason I suggested trying that way is because 1) It is quick and 2) It will store a code, but the car will still run fine. The idea was to see if the code was still stored in the future.
I gotta go back to work and get spit on. :cheers:
The black/white wire has nothing to do with diagnostic mode. That wire (if we are talking about the one by the brake booster) controls spark advance and if you disconnect it, you just don't get spark advance at the distributor. That is different from diagnostic mode.
The only reason I suggested trying that way is because 1) It is quick and 2) It will store a code, but the car will still run fine. The idea was to see if the code was still stored in the future.
I gotta go back to work and get spit on. :cheers:
Thread Starter
Heel & Toe
Joined: Mar 2001
Posts: 17
Likes: 0
From: Germany
Re: Maybe ECM Problems on my C4 ?? (HighHopes85)
I tried again to start the engine. I turned the key to the RUN position (ignition on).
In the RUN position the fan came up, the relays clicked and the "Service Engine Soon" light started flashing code 12. :U
That's the diagnostic mode, isn't it?
I turned the key to the start position, but the engine did not start.
The white/black wire is that one you can find at terminal B of the service connector under the dashboard (the one you connect with terminal A to switch to the diagnostic mode).
I made a picture, but I can't add it. Do you know how to add a pic?
In the RUN position the fan came up, the relays clicked and the "Service Engine Soon" light started flashing code 12. :U
That's the diagnostic mode, isn't it?
I turned the key to the start position, but the engine did not start.
The white/black wire is that one you can find at terminal B of the service connector under the dashboard (the one you connect with terminal A to switch to the diagnostic mode).
I made a picture, but I can't add it. Do you know how to add a pic?
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Maybe ECM Problems on my C4 ?? (Karsten90)
1) I tried again to start the engine. I turned the key to the RUN position (ignition on).
In the RUN position the fan came up, the relays clicked and the "Service Engine Soon" light started flashing code 12. :U
That's the diagnostic mode, isn't it?
2) I turned the key to the start position, but the engine did not start.
3) The white/black wire is that one you can find at terminal B of the service connector under the dashboard (the one you connect with terminal A to switch to the diagnostic mode).
4) I made a picture, but I can't add it. Do you know how to add a pic?
2) Car can start when the ALDL is jumpered. It is called 'field service mode'. I don't recommend driving with it jumpered.
3) -k-...I thought you were referring to the tan/black stripe wire used to cut EST advance to the distributor.
4) Upload it to a server. Then use the tag like this...{img}http://www.mypicturesarehere.com/picone.jpg{/img} but replace {} with [].
