Code 42 Possibilities

[gijoe985]

I'm going to go look at a 1990 Talon TSI AWD today that is for sale.The guy says that it doesn't run because the fuel pump is bad. HE says a mechanic looked at it for him and old him that.He mentioned the OBD I check port, and since he didn't seem to know much about cars, I am assuming this is how the mechanic diagnosed it. If the car IS getting a code 42, I was trying to figure out what things it could possibly be.

Bad pump
Fuel Relay
Fuse

I've read that the capon the ECU going bad, or coming off is common.

"Every time I've seen someone get a 42 it was due to leaking caps." -Steve

How do I check for leaking caps?
When I check it out, should I first check for codes, then for power at the pump, then check the ECU? How would I check the relay? Where is that located? I haven't owned a DSM before. Still learning my way around the car by reading forum posts. Thanks

 

[Auto RS T]

To check the caps (ECU capacitors) Unbolt the ECU from behind the radio and unplug it. Unscrew the 4 screws (they strip easily)that hold the covers together. Once the ECU is open smell it and see if it smells like fish. You may also notice some acid damage on the board near the capacitors.
That is basically as far as we can look at it, to have the ECU inspected in detail you can have it sent out to someone reputable.

I personally would check the codes and see what you come up with.

http://www.dsmtuners.com/forums/art...out-scantool-cel-testing-1g-turbo-models.html

 

[UKNOWHO]

I'm going to go look at a 1990 Talon TSI AWD today that is for sale.The guy says that it doesn't run because the fuel pump is bad. HE says a mechanic looked at it for him and old him that.He mentioned the OBD I check port, and since he didn't seem to know much about cars, I am assuming this is how the mechanic diagnosed it. If the car IS getting a code 42, I was trying to figure out what things it could possibly be.

Bad pump
Fuel Relay
Fuse

I've read that the capon the ECU going bad, or coming off is common.

"Every time I've seen someone get a 42 it was due to leaking caps." -Steve

How do I check for leaking caps?
When I check it out, should I first check for codes, then for power at the pump, then check the ECU? How would I check the relay? Where is that located? I haven't owned a DSM before. Still learning my way around the car by reading forum posts. Thanks

have a buddy listen for the pump while your cranking. if you remove the ecu and smellys funny id say def. ecu. which is good for you because you can use the ecu to haggle down the price. keep in mind u can get a good used non eprom for about 100 bucks!!

 

[gijoe985]

Anyone know the tools needed to check that? Off the tops of your heads? I'm bringing a set with me, but it isn't exhaustive.

 

[UKNOWHO]

philips screwdriver, and a 10 mm socket 1/4" should be fine. the ecu is located behind the radio, remover the carpeted sides of the console with screwdriver, then go behind where radio is mounted.

 

[steve]

Yep. Phillips, 10mm, and a voltmeter. A 1.5' jumper wire would handy to connect the fuel pump test connector to the battery positive.

Code 42 is caused by the ECU not seeing battery voltage showing up on pin 13 when the ECU is trying to run the fuel pump. The connection between pin 13 and the FP power line is in the 1G tech manual and the '90 FSM but missing from the later manuals even though it's still in the wiring.

 

[gijoe985]

Well I showed up, and unless I did something wrong, i think I'm getting an ECU code. All I go was a constant voltage from the 1 & 12 pin.

 

[steve]

Constant 12v output meant the ECU was getting power but wasn't working.

 

[absolute_DSM]

I would defenitaly pick up a spare ECU, swap in, and try it. You may get lucky and it may run.

 

[gijoe985]

I wish I knew how to combine this with my new thread, but where do I find an "extra" ECU to swap in? I know they can be found cheap online, but NAPA is like $500. And it's for a 1990, I've noticed that most ECUs on ebay are advertised for 91-94, why not 90? Or is that an overlook on their part?

 

[50trimmed1g]

A 90 ecu is different from any other 1g ecu!! You can install a 91-94 ecu in a 90 but you have to switch pins 6 and 14 for the ecu, you'll need a 91-94 coil pack and harness, 91-94 power transistor unit and harness, and a new gauge console.

Here is some info I pulled up----> converting a 1990 to a 1991-1994 ecu system

 

[GVR4592]

That's the old school, expensive way to do it.

This is the easier, cheaper way.

KEYDIVER Chips -1991+ ECU in a 1990 DSM