gchu

I have an 88 Iroc Convertible which I only put on 500 miles/year on it (thought it has over 155K miles on it)... Tried to start it up this spring and it wouldn't start. I always use STABIL in the tank and did run it during the winter and it sits in a garage with a battery maintainer

It cranks fine... Did notice that when I turn the key forward (not cranking), the Engine Light is flashing code 12 repeatedly, never noticed that before, but no other codes flash.... Is this flashing of code 12 normal?

I did swap the the fuel pump relay as I noticed that I didn't hear the fuel pump running, but no difference (still didn't hear it running).

Thought it was the fuel pump so I unplugged the fuel pump relay connector and jumped the 12V constant hot (orange) to the fuel pump pin with my trusty paperclip/code displayer and the fuel pump did run

I tried to use my Fluke multimeter to see if I got a signal from the ECM at the fuel pump relay connector (the thin blue line and ground), but didn't get anything.

So I swapped the chip out the ECM (I had a hypertech chip in it) and put the original OEM in it - the hypertech has been in for over 4 years so I new it ran with it

No difference....

Even after jumping the fuel pump to make it run, I still did not have any fuel pressure at the shrader valve by the TPI plenum

So I went and got starter fluid and sprayed the MAF intake screen but still not start

Was going to try and replace the entire ECM since it wouldn't start even with starter fluid (had thought it might have been a clogged fuel filter but that shouldn't stop it from starting on starter fluid... right?)

Help! Any ideas/suggestions?

Thanks

z28romance

got me stumped. you wouldnt have, by any chance, the ALDL grounded out?

gchu

I don't think the ALDL was grounded out as I used the paperclip to jump the fuel pump relay connector.....

My next thought was to drop the ECM again and check from a short when I unplugged the connector for the ALDL to ground at the ECM harness connector

Figured I would try that before bucking up for an replacement ECM

Curious, when people turn their ignition on (when the car is not running - idiot lights on) does their SES light flash code 12 or is it just solid? Thought it was just solid, but it's been such a long time since I paid attention to mine when it used to start :-((

Second question, if the ALDL is grounded (ECM flashing code 12), does your car start?

Thanks

z28romance

My SES stays solid with the key on before start. the only time it has ever flashed "12" was when i grounded out the ALDL. I have never tried to statr the car with the ALDL grounded, most tech manuals say you shouldnt. if yours flashes "12" upon key on i would say you have a wire grounding out or your ECM is toast IMO.

gchu

I ordered another computer from Ebay, should get it next week... In the mean time, I pulled the old computer out and when I checked at the ECM plug to see if ALDL pins were shorted, it was :-(( There was NO paper clip in the ALDL connector

Before I plug in the replacement computer, I know I need to take care of the short.... So one of my thoughts is to cut the wire near the ECM connector (according to the wiring diagram it's the white/black wire)... If it leave it clipped, would it cause any other problems? Figured I would just wire it to a switch so I can still get my SES/ODB codes... Has anyone else tried this?

I love my IROC convertible, but am getting very tempted to sell it :-((

Any thoughts/insite will be greatly appreciated!

gchu

Well.. Got the used ECM from eBay... Plugged it in without cranking it and still got the flashing code 12 and no fuel pump humm/whirr :-(( Drank a Guinness for courage and clipped the aldl line by the ECM... No flashing code 12 and the fuel pump fired up! Checked the Schrader valve and got the comforting mist of fuel come out :-))

BUT... It still wouldn't start! :-((

Not sure if clipping the wire would prevent spark (don't see how from the wiring diagrams)... But what's the easiest/best way to check for good spark????

schlegel94

you know code 12 means nothing is wrong correct

gchu

From what I've read about it was that code 12 is only suppose to flash when the ALDL data line pin is grounded to be in "diagnostic/error code" mode... Unfortunately, mine was flashing all the time. There has been a number of posts about starting the car when it is in the the diagnostic mode... Some have commented that it could damage the ECU so it was not recommended.

With my original ECU, I did not hear the fuel pump running/priming when I cranked the engine, nor did the fuel pump run/prime when I plugged in the replacement ECU (without cranking the engine, just turned the key forward). Even with the replacement ECU, it was flashing code 12 (expected as there appeared to be a short which "permanently" grounded the ALDL diagnostic line).

After I clipped the line, the SES was solid (no longer flashing code 12) and the fuel pump primed (I verified that the fuel was getting to the engine at the shrader valve at the top of the engine - there was no spritz before)

Unfortunately, it still wouldn't start.... My next step was to check on the ignition part of it..... Was going to get a spark control module to swap it out as it didn't seem to be too expensive but was looking for any recomendations from others on how to check the ignition circuit.... I'm afraid that the harness may be my issue so may have to replace that.... Has anyone replaced their harness? How hard was it?

Thanks