'90 4.5 No Cam Sensor Reference Signal Journey Through Hell!

[Sevillian273]

Ok. Caddy gurus, I'm going to pick your brains! I've been reading this forum for months and I have much faith in you guys!

I have a 1990 Seville 4.5 with just over 60000 miles and Ive been dealing with a constant code e041 as long as Ive owned the car. Sometimes the car stumbles upon acceleration from a standstill and has overall less power as if Ive retarded the timing. The symptoms are intermittent and usually last a couple of days however the code e041 and CE light always remain current no matter how many times I clear the codes. When Im not experiencing the symptoms the car runs excellent! Smooth acceleration, plenty of power, etc. Its such a tease!! Ive cleared the code while the car is running good like this, but the light and e041 come right back within seconds. The symptoms are intermittent but the problem seems to be constant.

So heres how Ive gone about troubleshooting...

-Replaced Cam sensor(duh,right?) Didnt help. New one and old one test within Haynes specs.

-Delco plugs, MSD superconductor wires, Accel Super Coil, New Ignition Module, Msd brass cap&rotor. No change.

-Checked pickup coil. Tests within 500 - 1500ohms as per haynes manual.

-Checked continuity from every wire inside distributor all the way to the EST 5 pin connector. All test good.

-Checked continuity across connector. Tests good.

-Base timing is @ 10 degrees BTDC

Other seemingly unrelated fixes Ive tried:

-Replaced EGR valve and Solenoid. No change.

-Cleaned EGR manifold tubes + Seafoam. No change.

-Tried EGR block off plate for sometime to eliminate the possibility of an EGR issue. Still nothing.

-New fuel filter. No change.

-New Batt, alt, coolant flush, thermostat. Nothing.

-Disabled Evap system temporarily to eliminate that possibility. No changes.

-Visibly traced all vacuum lines. No leaks.

-New oxygen sensors. No change.

-Disconnected A.I.R. pump output. Nothing.

-TPS, ISC, and minimum idle calibrated to spec. TPS and ISC also test good. Still nothing.

Ok, now HERES THE KICKER:
After all this trouble shooting I figured theres got to be a break in the line somewhere between the cam sensor and the ECM. The schematics in the Haynes manual identify this as a single brown wire with a white stripe which I have confirmed by looking in the distributor. This wire goes from the sensor all the way to and beyond the EST connector. According to Haynes it goes directly from there to the ECM, nothing in between. Sounds simple right? I have located this wire at the ECM also. It is the ONLY brown and white wire going into the ECM. I tested the continuity of this wire from the distributor to the ECM and got none. BINGO!....right? I thought I'd found the problem so I made a jumper wire to go from the wire at the distributor to the same wire at the ECM, but when I connected it the interior lights come on!!! WTF??

The only thing left to do that I can think of is to replace the ECM and/or entire distributor including pickup coil but I cant spend anymore money chasing this problem. This ghost has been haunting me for as long as Ive owned the car(about 11 months) and it it still drives me crazy. If anyone has experienced this or anything similar, any tips, comments, suggestions, ANYTHING would be MORE than appreciated!!

Please forgive me for such a long post. Its the best I could do to sum up this 11 month journey through Cadillac hell!

[Sevillian273]

Luckily someone who read this thread was nice enough to scan the trouble tree from the FSM and email it to me. So today I printed it out and dove on in there. Turns out that what I thought was the ECM was actually the BCM!!! I feel like such an ass! Did I mention this is my first Cadillac? So anyway, Ive got continuity from the distributor all the way to the ECM connector on all 5 wires. The results from the FSM procedure indicate that I need a new ECM. What a relief! This whole time I thought I had some crazy short between the interior lights and the distributor! Ill post the results after I get a new ECM. Until then, I hang my head in shame!

[carnut]

And buy a factory service manual. You WILL need it eventually.

[Sevillian273]

You can bet on it! The damn Haynes book for my Seville covers 3 Cadillacs, an Olds, and a Buick all in one. Its very vague on many subjects ESPECIALLY on the PCM / BCM location! As a matter of fact, when I was calibrating the TPS and ISC motor, Haynes said to start at a minimum idle of 525rpm, so I went by that and the car was sailing. Then I read somewhere on this forum to use 450 according to the FSM and all was well after that.

[Sevillian273]

UPDATE!! Just replaced my ECM and no more E041!! The car runs great now! The old ECM turned out to be a remanufactured unit also. Must've been from a junk yard or something. I suffered for 11 months with that and all I had to do was change the computer!!

[79malibuonblocks]

Originally Posted by Sevillian273

UPDATE!! Just replaced my ECM and no more E041!! The car runs great now! The old ECM turned out to be a remanufactured unit also. Must've been from a junk yard or something. I suffered for 11 months with that and all I had to do was change the computer!!

no shit? read my post......91 deville dead miss

[OlderSchool]

Yes, like carnut said get the factory service manual on eBay or something. Run the codes and it will get a you a long way towards figuring out the problem.
My 87' Coupe Deville has diagnosed every problem itself except one. You just need the Service manual to read the codes and follow the flow charts. A good voltage meter (digital) is a must. Good Luck!