Sonny_T

I have an 85 TA HO, 5 speed Quadjet Electronic Choke, MC Sol

-Reset ECM via disconnecting battery.
-key on, no click at MC Solenoid, nothing.
-Took of MC wire plug, key on, Voltage at pink wire at MC plugs is 12.
-Connected MC Sol directly to battery pos/neg and it clicks during
connect/disconnect of battery cable.
-Put back MC sol to the plug, key on, no click at MC.
-Code 54 shows.

Where do I began?

John in RI

iTrader: (167)

Most likely an ECM problem,... possibly the chip or wiring.

mlbinseattle

^ What he said.

Check to ensure you have continuity between the ECM and MCS (Light blue wire between pin 18 of the ECM and the MCS). Also, check to ensure that you're getting 12VDC on the other MCS wire (the pink/black wire). If both checks look good, then you have a possible ECM issue.

The 12VDC to the MCS appears to be the same 12VDC that powers the ECM, and it goes through the ECM/IGN fuse before it goes to the ECM and MCS. The fact that you're getting a code from the ECM says that the fuse should be good and that you're getting ground connection(s) to the ECM.

Sonny_T

I pulled both connectors out of ECM and put one lead of probe in pin 18 of one connector, and pin C of other connector. Turn key on/engine off and found resistance to be 25 ohm -ensuring me that blue wire connectivity from MC solenoid all the way to ECM connector is good.
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First ECM was old and bad so I put a second ECM.

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It seems to be this car will not do well in carb without a working ECM, and finding a good working ECM is like looking a needle in hay. That in turn means it will not pass emission in NJ.
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Putting LS1 is not a good option in NJ when comes to Street legality as car is not designed for 300+HP.
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I can not get rid of Computer as VIN will say it had OBD1 diagnose port and Jersey emission will probe it.

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Any suggestion.

mlbinseattle

Do a Google search. There are several sites that sell ECM's for these cars. Prices are reasonable, too.

Damon

Rebuilt (even new) ECMs can be had for very cheap bucks. The ECMs were used on scillions of GM cars of that era. You just need to swap the chip from your factory ECM over into the new/rebuilt one.

I replaced one using an old junkyard ECM out of a Sunbird or Grand Am or something- totally different application, but used the same ECM (Hollander interchange manual said it would). Swapped the chip over, installed, worked perfectly.

Sonny_T

Finding ECM is not the problem, I can even buy a new one at GM store for $150, it is the EPROM-DLB is the problem. GM doesn't sell DLB prom and rest are rare to find and old, not sure if they are good or bad.
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One, right now I am using is from Google/ebay and getting code 54 where my MC is good and clicking and wires are good.

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Moates doesn't have DLB bin file.

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mlbinseattle

Sounds like you may need to program your own. There's an entire forum for that on this site.

John in RI

iTrader: (167)

What is the factory ECM code (3 letters) and what is the factory PROM chip Code (4 numbers) ??

I might still have 1.

Sonny_T

ECM 1226865
Prom: 4303-DLB

Sonny_T

John RI,

I see you have 84 with LT1/T56. How is the State emission inspection in your place.

John in RI

iTrader: (167)

I live in RI and my Berlinetta is registered with the state as an "antique". Any car over 25 qualifies and is allowed limited with a maximum amount of miles per year allowed. An antiuqe does not require any state inspection at all. ( I think my Berlinetta Inspection sticker is from 2006.) We can also register a car with a "combination" plate. This allows the car to be used daily with no mileage restriction, however the car must pass a SAFTEY inspection ( NO SMOG failure possible. ) They WILL put the car on the SMOG machine and record the numbers,..... but a 25YO car using the combination plate will automatically pass the SMOG test.

My "HO" ECMs are from 84's; 'CJW' ECMs ( 1226455 ) One is for an automatic ( 5816 ) chip for Federal emissions & the other is for an 84 Stick ( 5822 ) for Federal emissions.

More importantly....... I found a couple 85 LG4 ECMs while I was digging around. ( 1226865 ) Feel free to send me a PM for details if you havn't found a replacement yet.