Marcho Polo

I tried it once and it didn't work out too well. Too much noise or something and the eprom wouldn't read correctly. I know it's been done before, I think Mike Davis did it.... but I had no luck. :confused:

GRX

I just did this to my car. Originally, I thought of moving only the ePROM somewhere convenient, say, under the dash, but I considered the electrical noise that might come from the ePROM circuitry. After all, the ECM is shielded in an aluminum case. ...and, all the electronic gremlins that would come from bad connections to the GM printed circuit board. The ePROM connector that GM uses is very unique and finding a RELIABLE mating connector proved next to impossible. So I did the next best thing and moved the whole ECM to a more accessable COOLER place(it gets mighty hot under that dashboard): under the passenger seat. There is plenty of room there. I made a mounting platform and secured the computer there. I routed the harness down the side of the footwell and back along the side of the car attaching it to an existing harness. The harness I made consists of less than 57 circuits of 18 gauge wire. For my car, I chose a length of about 80 inches total harness length. All splices need to be soldered and insulated with shrink tubing. Works GREAT! No electrical noise, a COOLER location, hidden, but accessable when you move the seat completly forward. EPROM changes are a snap. Emergency ECM changing are easy too(I carry a spare ECM). Normally this area under the seat is unused. Maybe the coolest spot in the whole car. If you want I can take a snapshot or two and post them.

18carfan

What a great idea! I've been putting off converting to a MAP setup but have been considering finally getting it done. One of my concerns was going to be how to get the ECM back up in the dash with the wires coming out of the side of it instead of the end. I too would be interested in seeing som pics. Where exactly did you route this extension harness and is it hidden well? -Jeff

88L98

GRX, you are a brave, brave man. :D i dont think i could cut/splice into my wiring harness like that. only way i would do it is if someone had some kind of plug that connected to the original harness like an extention cord to extend the ecm to another location. if you are going to do this, the number one thing you need to worry about is interference

18carfan

I would think that extending the harness for the inputs/outputs to the ECM instead of trying to adapt a ribbon cable or some kind of extension for the prom would be a lot less prone to interference. A donor ECM would be the best way so you could use the connector for the harness from it. The plugs that are part of the vehicle harness are easy to come up with. -Jeff


[Modified by 18carfan, 6:36 PM 8/5/2001]

GRX

I thought about getting a donor ECM connector but it's a right angle, double row connector that is designed for printed circuit use. Not a reliable way to go. Soldering to the leads would prove unreliable. Checked out the GM rich wrecking yard and sorted through a variety of connectors but to no avail. The ECM connector is a high density connector that is used nowhere else in the car. I was hoping to find a male pin, free hanging, connector. Found alot of female pin connectors. My 85 has 2 connectors, a 32pin and a 24 pin. Later years only use one connector? I probably could have found a connector from a GM parts book but did'nt have the time or patience! Instead, considering that I will probably be buried in my car, opted to perform major surgery. A removable connector harness would be good from a resell viewpoint, but I'm not planning on selling my beast....too many mods plus I 'love' my vette. What would I do with my spare time??? Anyway, I am very meticulous with anything I do and did a professional job. I got various colors of 18 gauge wire(80" length, each wire), and started the job. Took me about 3 days after work, to complete the job, but it was worth it. No interference on the radio. It takes concentration and a good left elbow. Mine was killing me on the third day! I had a pitfall: GM decided to use the same color wire in the connector a variety of times. No biggee, they were the same signals, basically; but in one instance, GM used a black/pink wire for TPS 5Volts and another signal. Well I reversed these! Soon, after some Diacom testing I found what I had done. Fix it and luckily the ECM was OK! Implementing a removable extension cable is a good idea but it is a potential source of trouble. Its been my experience that GM connectors tend to build a film across their contacts. Introduce one more set of connections to the ECM and there is one more chance for a problem. Sort of an extreme view but worth considering. If you have a GM shop manual, good soldering gun, good wire, shrink tubing and LOTS of patience in doing a quality job, then it will work fine. I'll try getting some pics on the installation posted this week.
Sorry for the book.


[Modified by GRX, 11:18 PM 8/5/2001]