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1g swap in a 99 gsx

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r1991_4g63t

10+ Year Contributor
704
1
Jun 26, 2008
Bellevue, Nebraska
ok guys im not new to DSMs just been a while and after 2 months of searching threads and not finding answer im looking for help. I have a 99 gsx that ran when the original engine locked up, i put a 6bolt in it that ran when pulled from another car. turning the key it will not crank over, jumping the battery to the start solenoid it cranks but thats it. i seem to have power coming out of the starter relay behind the radio but i can deal with that later. cranking the car with the key on should let it fire similar to roll starting? i have the harness to hook the 1g CAS up and as of tonight installed a brand new CAS but its still the same. ive been trying to get this running for far too long and am reaching out to the dsm crowd before taking it in as im stuck and have no more ideas. any suggestions would be appreciated
 
What problem are you trying to solve first? No crank or no start? If you're saying you'll just crank it manually by jumping and leave the key on so it will start....yes that should work assuming there is power to everything. You could still have a probkem since the car wont crank with the key. Id solve the crank issue first or at least make sure ecu has power with key on.
 
A quick and dirty test turn key to on. Check engine light should come on for 5 sec then go out. Key off you should hear mpi relay click off a few sec later.
 
If your not running the 1g cam sensor, you need to so the ecu gets a crank signal (the 1g CAS produces a simulated crank sensor signal)

I dont know about other CAS swap harnesses but with the RRE one you have to take the blue wire from the 2G CAM sensor plug and solder to the white wire coming out the CAS harness

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If your not running the 1g cam sensor, you need to so the ecu gets a crank signal (the 1g CAS produces a simulated crank sensor signal)

I dont know about other CAS swap harnesses but with the RRE one you have to take the blue wire from the 2G CAM sensor plug and solder to the white wire coming out the CAS harness

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This is the harness i have and how it is wired currently, the CAS i have is from a 91.

A quick and dirty test turn key to on. Check engine light should come on for 5 sec then go out. Key off you should hear mpi relay click off a few sec later.
I will try this, i know the CEL does come on but im not sure if it goes after a certain amount of time. or do i remember hearing a relay shut off after turning key off.
 
Just checked and the CEL does turn on and back off after a few seconds and I do hear the relay click when key is turned off.

I also checked again to see if I have power at the black/yellow wire coming from the starter relay again with key in start position and I do, as well as hearing the fuel pump kick on when in start position
 
The black/yellow wire goes to the ecu at B-56 PIN71 and to intermediate connector A-34 . Check to see if you are getting power at both points when cranking.

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The black/yellow wire goes to the ecu at B-56 PIN71 and to intermediate connector A-34 . Check to see if you are getting power at both points when cranking.
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A34 is a connector between the relay and starter? ill check this tonight that could be part of that issues. ill check the ecu as well.
 
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Yes. Im pretty sure its this one

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its the only connector between the relay and the starter solenoid
 
It cranks with the key now, had to cut Into the loom as they were on opposite sides of the engine. Gonna kick a buddy in the nuts tomorrow. Now on to other things, it's still not starting
 
Are you absolutely positive the CAS is good? Is it brand new ($500 roughly), or used, new to you, but known to work? I'm only asking because a few years ago I was having intermittent starting issues and my CAS was the resulting problem. The unit itself was in great condition, but it failed. I luckily found one in the salvage yard that had a broken casing, but mechanically it worked perfect. No issues afterward, and ended up buying a used, known-to-work CAS and that problem hasn't returned since 2013.

Also, make sure the CAS is installed properly. If it's in right, no problems. In wrong, it'll be 180 degrees off time.

180 degrees out
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Lined up correctly TDC Cyl 1
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I bought it brand new Monday, also tried it both ways just to be sure
 
After looking more into how the wiring harness could be hooked up wrong I found the connector for the coil and the connector for the cas harness are the same but with different colored wires. According to the diagram I got from mitsu the coil is a black/ white blue/red and blue/black. This is the plug that was hooked up to the cas harness. Have to extend it to reach the coil so it will have to wait til tomorrow. If I'm not wrong this could definitely cause the issue I'm seeing?
 
I dont know about other CAS swap harnesses but with the RRE one you have to take the blue wire from the 2G CAM sensor plug and solder to the white wire coming out the CAS harness

The RRE CAS harness has had a plug that plugs into the 2G Cam sensor harness connector for a little while now.
 
After looking more into how the wiring harness could be hooked up wrong I found the connector for the coil and the connector for the cas harness are the same but with different colored wires. According to the diagram I got from mitsu the coil is a black/ white blue/red and blue/black. This is the plug that was hooked up to the cas harness. Have to extend it to reach the coil so it will have to wait til tomorrow. If I'm not wrong this could definitely cause the issue I'm seeing?
Id say thats your problem.

The crank sensor wires are
red
blue/white
black

the coil wires are
blue/black
blue/red
black/white

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The RRE CAS harness has had a plug that plugs into the 2G Cam sensor harness connector for a little while now.

Good to know, thanks for the info.
 
Yeah, pisses me off that something so simple kicked my ass so long, not the whole problem though, popped once but still not starting, going through it tomorrow. But yeah 1g coil is close to 2g crank sensor and vice versa buy same connector
 
Thanks for all the help guys finally got it running just need to adjust timing and change a few other parts so I can drive it. Turned out to be the cas and coil plugs being backwards and the plug wires werent right. Previous owner had them on 1234 :ohdamn:
 
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