91 buick park avenue ultra

[17ford]

i have a problem with no spark at first it would run for awhile then die after cool down it would crank up run for a while and so on so i have put anew ignition control module crank sensor and cam sensor and it ran good for a while now it wont start at all still no spark my coil pack is good according to a ohm test but i know they can get weak when they get hot and kill the icm any suggestions?

[HotZ28]

Do you have the Magnavox or Delco ICM/coil pack?


You can have the ICM tested @ AutoZone, however, the test may not be 100% accurate!

This is a little “shop secret” that you can try to see if the ICM and the crankshaft sensor circuits are working. Connect a halogen headlamp to the spade terminals that mate the ICM module to the coils. A headlamp is recommended here because it puts more of a load on the module than a test lamp. If the headlamp flashes when the engine is cranked, the ICM module and crankshaft position sensor circuit are functioning. If not, you must replace one or the other, or both!

[17ford]

magnavox coil pack

[HotZ28]

Conduct the test and if the Magnavox ICM has failed, you may want to consider changing to the Delco system. Very easy to do!

[17ford]

do u know what the codes 41 and 42 for the obd1 system is for this car

[HotZ28]

Code 41 can be either the cam or crank sensor
Code 42 is the EST (electronic spark timing)

One of the more critical functions of the ICM, is the electronic spark timing function. The EST function controls the engine timing advance and retard. Of course, we all know that in order to have reliable starting functions, the timing has to be accurate. The other function of the ICM, is to turn off the current to the coil. When the CPS signal is made, the module turns the current back on. It has to be extremely accurate in when it does this..

[17ford]

did the test no flash so how do u fix the est could the computer be causing this problem i just put a new module and crank and cam sensor on it and even took the module back and got another going to take crank back tomorrow and try that and how could i test the connection at the module to make sure that it is getting good connection and it was suppose to have a brand new timing chain put on in may i check the magnet and it looks good and it was running good for awhile think maybe timing chain streached or got a tooth off ?

[HotZ28]

The only thing that would cause a total lack of spark would be the CPS, ICM or associated wiring. I have seen fairly new "aftermarket" CPS's go bad. I assume that you have good battery voltage and have power to the ICM. The EST is incorporated into the ICM, so it is a self-contained unit and not serviceable. Remove the ICM wiring connector and use contact cleaner on the terminal pins and then apply some dielectric grease to the terminal & reinstall. The timing chain is not the problem here.

[17ford]

i am not getting any voltage to the icm would the cps cause no voltage at the icm

[17ford]

problem solved had blown fuse in the relay center under right hand side of dash thanks for the help