carhunter

I hope some of you can help me. I have posted this problem in the ecm tech board but i cannot get any help. My 1991 firebird TBI 305 will no longer start after repairing heads. I do know what I'm doing in that area. The ecm which i believe "could" be my problem, is getting power by all appropriate wires. There is no fuel pump prime or fuel guage movement. The relay for the pump is good. I dismanteled the relay and ohmed the coil getting about 50ohms. The contacts are a little burnt from age but still work ( have continuity). The distributor gets skin melting hot. The wires are ugly but i see no evidence by thorough investigation that they are shorted. The tachometer likes to jump erratically all over the place on occasion.

I cannot get a ses light by ALDL jumping process. The bulb is good. The key is providing the proper resistance down the wires under the dash for the vats system. I cannot find the actual vats module though. The vats anti theft relay located behind driver side kick panel is my next suspect. I can hold key in "start" and nothing will happen but brake light illuminated and temp gauge goes all the way up. If i hold this start position with key and manually hold contacts of anti theft relay closed, the engine will rotate. After almost giving up, i went out one day and jostled this anti theft relay and turned the key, the whole car lit up priming fuel and all the good signs however, there was not enough power in battery rotate motor from previous havoc. I charged the battery with high hopes and now nothing. I wiggled and disassembled the anti theft relay cleaned with CRC spray,ohmed the coil and it tested good. The car is now a yard ornament once again. I am at my wits end and could really use some advice. By the way, i have even tried a brand new ecm for fixing the problem and it did not work. Please help

OrangeBird

iTrader: (1)

The key bit of info in your post is ;

" The Distributor gets skin melting hot "

This is , 100% most certainly , NOT normal and needs looked into before you can expect this thing to run . You can't even get it running and the Distributor is too hot to touch ? That's a screaming red flag that there is a problem with either the wiring , the ICM , or the coil (or any combination of the three) . Yes for certain , the no prime and no SES light with A&B jumped (and a good bulb) are symptoms also , but first and foremost would be to determine why the distributor is roasting .

carhunter

I checked the distributor coil with an ohmmeter as per an online instruction. It tested fine. I can test it again. Maybe its frame is not grounded enough. The driver side ecm and fuel pump grounds to the rear head have been relocated to a sufficient ground away from the block. It is really odd that those three ground wires were outputting between 8 and 10 volts. Not enough to spark though. But the car came alive like it is supposed to, after i knew those wires were acting as a dead short to ground. I believe 'something' is causing "something" to short out. I know that all fuses and fusible links are good. I checked them twice. Working backwards is very difficult here. I'll investigate the ICM today and get back with some news.

carhunter

I don't know how to bench test ICM. I had bought a new anti theft relay but it did not help on that side of things. Would a bad or dead shorted ICM make the ECM go hay wire and not come on to prime fuel system and light up dash?

I'm not or don't ever remember getting a security light for vats.
( its bulb is good as well).

I apologize for jumping around problems. I'm hoping that some symptoms might give a better idea of the issue.
UPDATE:
I disconnected white tach wire to remove that circuit for protecting my instrumentation (it does the following either way). With key in on position with a hot battery i have everything else hooked up to distributor and coil. When i pull coil wire off the top of coil it shocks around all over like the engine is running. I don't think it is supposed to do this shocking unless ICM detects rotation from distributor shaft ? I believe when the cap is in place, the coil sends a single and constant shock through the cap making heat develop through rotor button and heating distributor base. Or am i missing some knowledge here?

carhunter

I really need some advice/help here. If I cannot figure out what the issue is, the car is going to be hauled away. I'm going through a divorce and need technical advice for my car. Please help me find my problem!

gertie3993

iTrader: (2)

When my car stopped starting I checked all the grounds and they seemed fine with the multimeter, but when I connected a jumper cable from the engine block to the negative on the battery it started right up. It may be worth a try considering you moved those wires.

If the gauge is erratic you can check the wiring around the block, I found one of my wires had torn insulation and was shorting out on the engine block.

carhunter

Thank you very much. I will give it a try.

92RS shearn

An auto parts store can check your ICM. with no SES light though maybe it's the ECM?

carhunter

I have tried a brand new ECM using old prom. No luck. However, throughout the course of this madness the old ECM could have been damaged. I will not discount your input. I will also have auto store check my ICM.

carhunter

I had ICM tested. The part store showed me the results of the test. Everything inside the ICM worked except the "high rpm" part.
He said it should still start the car, but at a certain rpm it will shut down the motor. The high rpm circuit inside the ICM could be causing everything else to fail due to a possible short. I have not the funds to replace right now unfortunately.

92formulalukain

please someone helppp me im a youg guy not good with lights or electrical i have a 1992 firebird formula and the lights all worked fine and then all of a sudden they didnt had it towed home and now if the dome light is on wen u open the door but as soon as u flip the headlight switch it and all the dash lights go out like theres no power at the headlight switch and ive replaced the light part of the switch checked most fuses i kno were to locate please help meee any advise is appreciated

carhunter

Go and open hood, and disconnect both motors that flip up headlights. One of them might have shorted out causing entire system failure when energized. One or both motors could be causing a problem. They were designed with less than quality parts.

92formulalukain

just unplug them at the motors? and could that cause the dome light and tht annoying buzzer when the key is left in come on sometime n sometimes not the other day they worked fine till i shut them then they wouldnt raise up at all ima go try the motors unplugged now

92formulalukain

ima go try this now sorry to post twice im new here

carhunter

It's cool man. I'll do what i can to help you. My firebird is still dead in water.

92formulalukain

no luck man still no power but car starts brake lights work radio etc just no dash dome horn or head lights except for the rare times it decides to work right then everything works???

92formulalukain

anyone plz any ideas are appreciated my birds been down for wks now cause i cant drive it at night and work nights...

carhunter

If the lights come on and shut off when they want to (with headlight switch on), and no fuses are being blown there could be a bad connection. Especially a ground wire. If nothing is working at the moment, try turning what you want to work on, then gently wiggle wires under dash and wire harness going into firewall next to brake fluid reservoir. Sometimes corrosion can develop in the connections. If your problem goes away you have then roughly located the problem area. If you have done any repairs lately like putting in new headlight bulbs or a new cd player, retrace your steps and make sure nothing is pinched or shorted. Check ALL ground wires ( any wire that is fastened to body) near headlights and especially under driver side dash behind pedals. If these grounds become loose or rusty, that could be your intermittent light problem.

I'm not the best but hopes this helps some. I'll do my best to keep helping you.

92formulalukain

thanks man its night now and ive remooved the kick panels looked at all the grounds it does have a cd player in it after market...mayby one of those wires came loose let me explain it a lil better....if u open the doors sometimes the dome light will come on and if it does the buzzer by the headlight fuses under driver side panel will work..now if its out the radio in the car will work the car will start the brake lights work and both signals and heater and hazARDS but as soon as u try to turn the headlights or parking lamps on the dome goes out u cant even make it come on by the dimmer the buzzer only works wen it wants too i replaced head light switch but not the dimmer part of it i alsotried to get tht plug lose by the resivoir under the hood (brake) and i couldnt seem to figure out how to get it to come unconnected but ive wiggled all under the dash and still no luck the headlight motors wont run when the switch is on either ,,,like theres just no power saying tht the lights r on

92formulalukain

theres a blk box in the passenger side kick plate what is tht thers alot of wires going to it and it says telcom ..on it

carhunter

Power door locks. There is also an anti theft relay near there with heavy gauge wires. It sounds to me like there is something wrong with your headlight switch area. Is the switch new or used? The dimmer operates the dash lights brightness as well as turning on dome light. The dimmer may have a short inside itself. I would open the switch area up and thoroughly check wires for fraying and cracks as well. The dimmer probably needs to be replaced. keep in mind that if there is no "short" or blowing fuses and good grounds, 99% of the time there is a failure of the switch, or dimmer in this case, to complete the circuit for operation.

As for aimlessly replacing parts to eliminate a hidden problem, don't feel bad. I know it is expensive and feel your pain. Sometimes we can only do what we are able.