Basket Case GN with Multiple Fault Codes


New Member
Aug 13, 2003
I have a 1987 GN that I bought new, but have not driven so several years. I do drive it around the block occasionally to keep it going, but it kept running rougher and rougher until it would not start anymore. I have no spark at the plugs and no spark coming out of the coil. I also do not have an SES light when I turn on my ignition. I have read several posts about trouble shooting this problem, but most are over my head. I did hook up my OTC Monitor 4000E (don't make fun of my ancient technology - it is all I have) to the portal and pull of the following codes in the order of most recent. Could someone please look at these and give me an idea what I need to replace? Code 55 (ECM Error); Code 52 (Cal Pak Error); Code 51 (Mem Cal Error); Code 45 (02 Rich); Code 44 (02 Lean); Code 43 (ESC Ckt Error); Code 42 (EST Error); Code 41 (Cam Sen Ckt Error); Code 34 (MAF GM SEC Low); Code 33 (MAF GM SEC High); Code 32 (EGR Ckt Error); Code 31 (Waste Gate SOL Ckt); Code 25 (MAT/IAT Ckt Error); Code 24 (VSS Ckt Error); Code 23 (Waste Gate SOL Error); Code 22 (TPS Ckt Volts Low); Code 21 (TPS Ckt Volts High); Code 15 (CTS Ckt Volts High); Code 14 (CTS Ckt Volts Low); and Code 13 (02 Ckt Open).

Any help would be appreciated.
Remove the ECM at the kick panel and check the plug and socket for corrosion. Remove the chip from the ECM and CAREFULLY clean the legs with a pencil eraser then reseat it.

If the main plugs aren't corroded put the computer back and see if you have a check engine light or if it starts.
I would go with a corroded ECM. Mine had the power pin corroded off and left me on the side of the road. Started looking and no check engine light. The fuel pump would not kick on ect.

I bought a new ECM from highway stars and new plugs from Caspers. The plug sucks to change but you need to change both. It took me 4hrs to solder it on.

Common causes for cars sitting would include checking the positive battery cable for acid leaching. I have seen this a few times over the years; the acid from the battery leaches into the terminal lug, up the wiring, and ultimately corrodes the copper wire on both the heavy cable - and - the wire that feeds the fuse link for the MEM feed (orange wire with single black connector). If the MEM voltage sags, it will cause multiple codes. The chip is generally intact if you actually get codes.

The second biggest cause is the ECM connectors. Look for any sign of white or green corrosion inside the ECM connector and on the ECM plugs. Water seeping into the connector causes this. If you find any at all, REPLACE both connectors and ECM. You won't be able to permanently fix it no matter how much contact cleaner you uses, and how much dielectric grease you apply. Once corrosion sets in on any terminal, the tin plating is compromised, and the connection resistance goes way up, so it's generally hopeless.

And finally, the C100 bulkhead - the big one near the power brakes on the firewall - fails easily. Same as above, once you clean off all the "gorilla snot" tar applied at the factory, you reveal the same corrosion on the terminals, both male and female. It's a big project to fix that corrosion since it involves the connector on the firewall that is part of the dash harness.

Aside from this, always check the four grounds at the back of the passenger side cylinder head, and also, the three fuse links at the starter post.

I just did a run of stock engine harnesses and sold out, mostly to guys who have intermittent electrical issues. Our turbo cars aren't getting any younger...