85 cadillac seville
 

I have the 4.1 liter motor engine service light keeps coming on while i am pushing gas petal when i let off pedal light goes off

when i am on the highway the service engine light comes on and engine idle changes

i brought to the garage but the only code it produces is code 52 - ecm memory reset indicator but i check the computer inside car and codes that came up are

12 - no tach signal
16 - generator voltage out of range
30 - idle speed control unit
52 - ecm memory reset indicator


does anyone have any idea what it could be

engine lite
 

Code 12 could be loose distributor connections or the distributor module
Code 16 could be generator having low output ,check voltage at fuel pump fuse with a voltmeter to ground, 10.5-15.5 replace ECM. If less than 10.5 or greater than 15.5 generator is questionable.
Code 30 very in depth testing of isc required three of the tests point to ECM and one points to replace isc motor.
Code 52 Faulty ECM
Without doing a lot of testing most things point to ECM. I would start by checking all and every electrical connection you can find,pull connection apart, clean with a fine wire brush and coat with dielectric grease and then reconnect. This goes for all ground points to the body and frame. Start with the connections at distributor and generator and battery. Good luck.

I don't know if this means anything but. I can a humming sound through radio while car is on

Hummmmmmmmm
 

You probably need a new condenser in the distributor.

85 cadillac seville
 

sorry the humming like sound is not coming from radio its coming from engine

but i found a ground wire thats not connected but not sure where it goes to

its connecting to back of engine compartment near firewall but the other end

is not connected at i am assuming it needs to connected to engine just sure where and could that cause a humming noise from engine

my lights dim occaisionally while driving and then get bright

this car is driving me crazy if its not one thing its another

i recently had oil pump replaced and then bolts to battery needed to be replaced because they wouldnt tighten and now service engine light came on and thats when the engine started to make a humming like sound

code 12 - 16 - 30 -52 was the codes that popped up reset and code 16 still coming back right away

and besides all that the timing bracket on fly wheel came off so i cant even set the timing correctly and im getting about 12 miles to the gallon.

at 3.60 a gallon here its killing me

well thanks for letting me vent

talk to soon hopefully with good news

Hhhuuuummmmm
 

Do you have the DFI on your engine??? That can sometimes hum if the injectors are worn. Did you manage to get the generator tested. The ground probably goes onto the hold down bolt at the base of another component. Caddys are fun aren't they?? The dimming of the headlites could be other ground issues.Hope you find the gremlins before you go off the deep end.

sharpenest
 

my 85 service now light does the same thing, checked and no codes show up, would like to know how to reset the light