Where can i find a vacuum light?

Check engine light/code 1294

• QUESTION: hi roland i have a 1996 dodge caravan 2.4. it has about 82,000 miles on it. i failed inspection because my check engine light does not work. we have changed the bulb no light , s we changed the cluster and it still does not work. someone told me it may be a fuse or a relay. i am not sure which fuse i should change..i have two boxes. the one under the dash is clearly labled, however none say engine light or mil light so i am not sure which to change....will it share a fuse with something else? also is a fuse the same as a relay? i know the the computer/obd works because they are able to scan for codes my check question is code p1294. target idle not reached. we changed the egr valve and fixed a vacuum leak, and we reset it but the code still comes up, anything else it may be? car idles rough when at a a light, hesitates...when i go from stop to go or up hills....starts with a roar of force at times..or a sluggish start at other times. things we have done to car. new cam shaft sensor three years ago new fuel pump 1 1/2 ago map sensor 1 year ago tempature sensor about 6 months ago egr valve sensor, & fuel filter 1 month ago (when we first replaced the egr valve it kept stalling we had the idle adjusted ....was good for a day and went back to its old ways of a rough idle...when we unplugged the egr it purred like a kitten...friend at work said this was odd) starter, harmonic balancer, and power steering built 2 weeks ago. vacuum leak repaired and throttle body cleaned 1 week ago..... after repair car sounded much better for only a day...back to rough idle and code coming back up. we also changed the spark plugs a few days ago as well. please let me know if you have any ideas, i need to pass inspection and i am not sure which way to go. do you know where i can find out what fuses at what for the box under the dash and the second one under hood. thank you so much heather ANSWER: Hi Heather, Thanks for the detailed question with all the history. It helps a lot to know that. On the check engine light, there is not a separate fuse (or relay) for that function. The fact that you tried a replacement cluster to no avail would suggest that the problem is inside the powertrain control module proper, not the wiring or the cluster. The function of the light is handled digitally by a signal that is carried by the digital data bus between the pcm and cluster and since the other digital signals needed by the cluster do work that means the bus is good. So my thought is, since you can get the fault codes when needed and can check for them in the future when you sense a problem, why not simply 'fake it'. Otherwise you are looking at a replacement pcm and some shop time to program it. Here is what I would suggest that you do to get past inspection. Notice another similarly functioning warning light #such as oil pressure/abs# which automatically comes on when you turn the key to 'run', but then extinguishs when you start the engine. Remove the cluster and simply jump a couple of wires from one of those bulb sockets over the the check engine light bulb socket. Then put both bulbs back in their sockets #maybe it would be good to insulate the check engine bulb holder contacts from actually touching the circuit board so as to not feedback 12v to the circuit board#. The check engine light would then appear to be functioning normally. On the 1294 code, that suggests that the automatic idle control 'motor' in the throttle body is not doing its job. When the throttle body was cleaned that aic motor should have been remove so its tip could be cleaned along with the passageway and orifice that it controls could also be cleaned out. That is something you could do yourself to be sure it is done by simply unplugging it and removing it and then cleaning out the passageway with solvent and a q-tip. You can also check the wiring harness at the same time to notice any melting/damage to one of the 4 wires that is uses. You could also verify the continuity of the wires from the plug to the pcm: pin 1 gray/red to pin 57 at the pcm pin 2 yellow/black 49 pin 3 brown/white 48 pin 4 violet/black 58 The iac motor could need replacement but I would do this first. I would suspect there would be another code #0505# were the motor/circuits to be faulty, however. Look over the wires at the pcm plug to verify there is no problem at the other end. The last possibility is the pcm is bad #which goes along with the check engine light theory# but do that as a last resort. The fuse assignments are a bit obscure for me since I don't have the '96 manual and in any case the way they are listed is by circuit number not 'function'. But fuses are not an issue in your present situation anyway. If by chance the box in the engine compartment has a small bulge at one end, and the box under the dash simply has 28 fuse sockets and no plugs, then the '96 is the same as '95 and I do have that manual so let me know if that is the case. Good luck and let me know how this works out. Please "rate" my answer #see below#. Thanks, Roland ---------- FOLLOW-UP ---------- QUESTION: just one more quick question when i had my starter and balancer replaced a week ago the mechanic (not my usual mechanic) said that my timing belt was making a noise and i probally needed a new tensionor. i was wondering if this is something he would be able to hear? i know when i start the car at cold it makes a rattling noise on the passenger side under the hood,but once warms up it is gone.has done this since i had the van...could this be the timing belt? and could this cause the idle code to come up? i am tight on cash and my main concern being how i have a expired inspection sticker and have failed twice is to get this car to pass inspection, i would rather wait for the timing belt until next month if it has nothing to do with it,but if the possibilty is high that it does i will re-work my budget. thanks heather

• Answer:

  Hi Heather, Noises are difficult to diagnose the cause of, particularly at a distance. There are many moving parts on the front end of the engine (alternator/power steering pump/water pump/ac compressor clutch) so only if the mechanic was very familiar with that specific engine and could localize the source area would I conclude it is the belt tensioner. That engine fortunately does not have the risk of damage should the timing belt fail so I would not give it a high priority at this time. If you were involved with long distance travel then the priority would be higher to find what is making the noise. It is probably premature to get into a job involving the timing belt with only 82,000 miles on it. Inspection of the belt is the usual approach to belt replacement, say at 15,000-30,000 mile intervals, and when serious wear is identified to consider replacing the belt and tensioner at that point as a single job and replace the water pump then as well. I doubt that a tensioner problem would impact the idle speed problem. I hope that the simple rewiring of the check engine light will get you through the inspection, rather than a new pcm/selling the vehicle. Thanks for the rating/nomination. You are entitled to do it again if you are inclined. Roland