1990 Pont GP - 3.1L No Start; Code 42
1990 Pont GP - 3.1L No Start; Code 42
Car came in as no start. Replaced Crank Sensor, Wiring, Ignition Module. Bringing up Code 42. No continuous spark after first time trying to start.
Any suggestions? Thank you much.
Any suggestions? Thank you much.
- brianp87
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Re: 1990 pontiac grand prix 3.1 Lt. code 42
Why were sensor, wiring and module replaced?
Re: 1990 Pont GP - 3.1L No Start; Code 42
Thought it was a good place to start. Got no RPMs when trying to start it.
- brianp87
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Re: 1990 Pont GP - 3.1L No Start; Code 42
Check the injectors and there pulse
Re: 1990 Pont GP - 3.1L No Start; Code 42
Will a shorted injector mess up RPM Signal?
- ricmorin
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Re: 1990 Pont GP - 3.1L No Start; Code 42
Time for some testing. First thing is to scope the crank sensor. Make sure that signal is getting to the module. Powers and grounds to the module will need to be checked. By your description, there IS spark at first then it goes away? The ECM takes over spark control at 400 rpm, so the possibility of a bad ECM is there as well. Use the process of elimination. Check the Hi and Low reference lines from the module to the ECM.
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- brianp87
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Re: 1990 Pont GP - 3.1L No Start; Code 42
No you need to check voltage at the module to start. Then I would check inj pulse. Also check the wires to the crank sensor to see if they are possible backwards
- ricmorin
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Re: 1990 Pont GP - 3.1L No Start; Code 42
Possibly. Most drivers use discreet power supplies, but some of these older ecm's didn't work that way. Easy way to check is to remove the short.bakerauto wrote:Will a shorted injector mess up RPM Signal?
Ric Morin - Volunteer Forum Moderator, Shop Owner, ASE Master L1
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- brianp87
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Re: 1990 Pont GP - 3.1L No Start; Code 42
Didnt get done typing before you ric lol. Key point is to start at one point and test each component with the most likely being sensor
Re: 1990 Pont GP - 3.1L No Start; Code 42
Ok thanks for all the input. Going to pull the intake. Let you know what I find then. (Have checked all of the above)
- steven kiser
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Re: 1990 Pont GP - 3.1L No Start; Code 42
am i missing something here? why is the intake coming off? is there a loss of spark after initial crank along with injector pulse stoppage? look into ric's tip on 400 rpm. i'm seeing a note about a mem cal chip issue...........has anyone been monkeying around trying to juice this up with "computer chip" replacement? these systems are fairly simple but in their simplicity some are difficult if not impossible to properly diagnose. if you're testing continuity or ohms on this car please use the connector chart not the color guide. personally i always run into faded color issues on older cars especially when the harnesses and plugs are initially covered with a grungy mass of crapolla. this tends to lead to head banging. is the crank pulley seperating? have seen many of these, but as a rule not causing this particular issue.
never argue with a fool, they'll drag you down to their level and beat you with experience
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Re: 1990 Pont GP - 3.1L No Start; Code 42
Hmmm. So, we got a code 42. Generally in the past when I diagnosed that code using the diagnostic flow chart I found the problem. By replacing the ignition module, that possibility probably has been eliminated but there could also be a wiring issue between the ecm and ignition module but the ecm is also a prime suspect in this situation. I am not understanding why the intake is coming off as that has nothing to do with a code 42, unless there is other issues not mentioned. I'd be scoping the circuits between module and ecm. If they are good and there is a rpm signal, I'd be hunting an ecm.
- brianp87
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Re: 1990 Pont GP - 3.1L No Start; Code 42
what did you find out? Any luck or questions?
- brianp87
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Re: 1990 Pont GP - 3.1L No Start; Code 42
brianp87 wrote:what did you find out? Any luck or questions?
Re: 1990 Pont GP - 3.1L No Start; Code 42
Car still in the shop. Will keep you posted
Re: 1990 Pont GP - 3.1L No Start; Code 42
Just to give you an update on "our nightmare car". Ended up receiving "bad" ignition module from parts supplier!
- steven kiser
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Re: 1990 Pont GP - 3.1L No Start; Code 42
gotta love it. i learned the hard way assuming that replacement parts are good. when i test something and replace a part and if the issue still remains i start all over again testing. i chased a battery draw for day's before i tested the battery i gad installed. it was junk.
never argue with a fool, they'll drag you down to their level and beat you with experience
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Re: 1990 Pont GP - 3.1L No Start; Code 42
I usually test even a new ignition module with the tester I have here in the shop. It's surprising how many new in the box modules there are that are bad. What ya really gotta love is when ya open the box of a supposedly new one only to discover someone has had this one out of the box, installed it already and now I got it. GRRRRRRRR!bakerauto wrote:Just to give you an update on "our nightmare car". Ended up receiving "bad" ignition module from parts supplier!