Stubborn e041

[Guest GD 1277]

Hi new here maybe you have some ideas on my 88 Reatta with e041 cam sensor code. I have replaced everything including ecm, icm, cam sensor, magnet, and checked all wiring. I even took old computer apart and plugged into harness to verify contact on ic5. I went through factory service manual trouble tree and all tests good until looking for voltage on ic5. No voltage on ic5 and by accident after many hours of testing I found that I get voltage on ic5 only after starter engagement, the weird thing is when I have voltage on ic5 if I move the crank in any direction just the slightest amount the voltage goes away and to get it back I have to bump the starter. If I start the engine I have the proper voltage on ic5 and it is pulsing. It shows 50 HZ at idle but the computer still shows e041. Any ideas would be appreciated, I've thrown over $300 in parts at it and countless hours studying schematics and testing and I am exactly where I was when I bought the car 10 years ago. Buy the way the car runs fine with no other codes.

[Ronnie]

Welcome to the forum! Have you used the troubleshooting flow chart for code E041 (section 8D1-53) in the Field Service Manual to try and determine the problem?

[Guest GD 1277]

Yes I used the troubleshooting tree, all is well until the step that checks the voltage at computer terminal 1c5 key on engine off, it should be above 8v I get .007v. If I engage the starter it goes to 9.75 but if I move the crank just a degree or two in either direction it goes back down to .007v. If I start the engine the voltage is around 10.75v and it shows that it is pulsing 50HZ at idle.

Edited February 17, 2014 by MCHinson
Opened closed thread and merged threads. (see edit history)

[Ronnie]

The voltage changing when the engine moves to a different position is normal. It changes as the cam gear magnet passes the cam position sensor. I see no reason why you should be getting the code 41. I would check and clean all the grounds near the battery if you haven't done so.

Edited February 17, 2014 by MCHinson
Opened closed thread and merged threads. (see edit history)

[jbeary]

Hey GD, Jim Finn (who, along with Ronnie, is a great man) just did a post not even yesterday about this same thing. Look a few posts down called Cam sensor repair with JB weld and check out the link that Padgett (yet another great man) has posted with detailed directions for, what seems to me to be a solution to your issue.

[Guest GD 1277]

Jim, did the magnet repair 10 years ago and the magnet is still there.

[Guest GD 1277]

Ronnie, When I say I moved the crank and voltage goes away, the magnet is nowhere near the cam sensor, it seems that any change in position of the crank sensor is making the voltage go low. The ignition control module has 2 amplifier-buffers one for cam sensor to computer and the other for crank sensor to computer. Why do I not get voltage unless the starter is energized? Just as another test I am going to use a scanner on the ALDL connector to see if the code is really in the ecm or if the crt computer just thinks there is a code.

[Guest Mc_Reatta]

Are you talking about the reference voltage on the white/black wire from pin N of the ICM to pins C on the cam sensor and pin D of the crank sensor that's supposed to read 10 v when ignition is on?

[Ronnie]

You could still have a bad cam position sensor. I would rule that out first. Try this as a test. Disconnect the cam sensor. Turn the key to the on position but don't start the engine. Check terminal C to ground to see if it has 8-10 volts. Then jumper terminals A & C and test for cam signal voltage at ECM terminal BC5 (I'm looking at '89 FSM. May be ic5 in '88 FSM). You should have 8 volts or more.

If you don't have 8 volts or more at the ECM the wiring is bad or the ICM connections where the harness plugs in could possibly be faulty. A bad ICM is also a possibility.

If you do have 8 volts or more at the ECM... Remove the cam position sensor and test for continuity on terminals A & C. If the circuit is open the cam position sensor is bad.

Next take a magnet and hold against the cam position sensor and check for continuity. The circuit should open and close as you apply and remove the magnet. If it doesn't the cam position sensor is bad. Some say that magnet polarity doesn't matter and some say it does. Check with magnet turned both ways.

[padgett]

I think earlier you mentioned changing the ECM, did you transfer the original PROM or did you make sure the new PROM was for the same car/engine ?

[Guest GD 1277]

I replaced the ecm and used the old prom it was the right one, the original anbm. I don't get voltage on 1c5 at the ecm, cam sensor input, when I have key on engine off but if I bump the starter I get 9.75v and about 10.75v with engine running and it is pulsing at 50 cycles / second at idle and increases with increased engine rpm. I plugged a scanner into the aldl connector and got no info from the computer. Does the aldl interface with the computer on these cars?

[Guest GD 1277]

Mc_Reatta, I have voltage on the cam sensor connector terminals a and c and I have good ground on terminal b. It is at the cam sensor terminal on the computer that I have no voltage unless I bump the starter or start the engine then I have the proper voltage.

[Guest GD 1277]

Update, I think I found the problem. It just works different than the FSM says. Mine needs a wake-up signal from the starter. I gave it a wake-up signal and then started testing. With the cam sensor out of the engine I can turn off and on the voltage to the ecm on terminal 1c5. If I disconnect the crank sensor the cam sensor circuit will not wake-up by engaging the starter. Maybe there is something wrong with the crank sensor or maybe that is just how it works. Now for the problem. It seems the magnet is rubbing the timing cover and is worn down some. I lined up the magnet in the hole inserted the cam sensor and the magnet did not trigger the sensor, the voltage to 1c5 was not interrupted. So I guess the timing cover has to come off to see what is wrong in there. Thanks for the help; someone suggested to try the magnet on the sensor outside the engine and that got me looking in the right direction. I'll let you know what I find inside.

[Ronnie]

"Mine needs a wake-up signal from the starter." What are you saying needs a wake-up signal?

[Ronnie]

In the back of my mind I'm thinking that the magnet has to be inserted in the proper direction. Maybe someone can confirm. If that is the case maybe someone put yours in backwards.

Edited August 8, 2013 by Ronnie (see edit history)

[Guest GD 1277]

Ronnie, My ignition module does not send voltage to the ecm 1c5 terminal until after the starter is engaged. I don't have a clue why that is. Once I engage the starter and the cam circuit has voltage at terminal 1c5, if I disconnect the crank sensor, the ignition module stops sending voltage to the 1c5 terminal on the computer. When I put it back together I may try a new crank sensor to see if that will make the system work without first engaging the starter.

[Guest GD 1277]

Also, the magnet is in the proper direction, it is just worn down about 1/8 inch.

[Guest Mc_Reatta]

Yes, the magnet does need to be inserted correctly for it to work.

The magnet interrupter assy is meant to be inserted into the back side of the gear.

When used as a replacement and inserted from the outside thru the sensor hole, the lip of assy needs to be removed and inserted into the gear and cemented in place so that the 4 magnet tips can be seen by the sensor, or it won 't activate the sensor.

Bet you just installed it reversed. That's probably why it it rubbing on the sensor and timing cover too, as that ridge at the rear is fairly thick which sticks out if it's in backwards.

[Guest GD 1277]

No it is put in correctly, I cut off the flange so it could fit into the hole in the gear. At the time I just decided to try JB weld and I made sure it was installed in the proper direction. The JB weld works good because it is secure even though it is rubbing. I suspect the cam button spring is broken or missing allowing the cam to move forward and let the magnet rub the case. I'll know tomorrow when I take it apart. I first have to figure out what to do with the heater hose pipes. The pipe to the manifold is fused in place. I may cut it off and just splice with a short piece of hose.

[Ronnie]

No it is put in correctly, I cut off the flange so it could fit into the hole in the gear. At the time I just decided to try JB weld and I made sure it was installed in the proper direction. The JB weld works good because it is secure even though it is rubbing. I suspect the cam button spring is broken or missing allowing the cam to move forward and let the magnet rub the case...

Even if all that is correct, none of it explains why the magnet will not trigger the cam position sensor when you aligned them together. Something is wrong with the magnet or the sensor.

[Guest GD 1277]

The magnet is worn down to the point it is too far from the sensor. From experimenting the magnet has to be about .29 inches from the sensor to work. From careful measuring the magnet is about .34 inches from the magnet, just too far away.

[Guest GD 1277]

Well I took it apart and of all the dumb things, you guys where right I put the magnet in backwards. I ground the flange off the magnet and dry fitted it in the timing gear and I guess when I put the JB weld on it I somehow put it in backwards. I did not find any signs of the magnet rubbing the cover but the magnet clearly has been ground down by something. What I did find is the timing chain damper was broken and parts were in the oil pan, I don't know if the damper somehow got in front of the magnet and damaged it. The interesting thing is I found all of the plastic from the original factory magnet but not the magnet.