Initially we were unable to duplicate the intermittent no-crank condition on this Maxima.
|Vehicle : 1995 Nissan
Powertrain: 3.0 Liter V-6 4Spd. A/T
Symptom: Intermittent No-Crank
Some of the most interesting work days can start with some of the strangest problems. In this case, one of our customers with a 1995 Nissan Maxima was getting rather frustrated with us and her car. This customer had been in to see us one week prior with the same complaint but we were never able to duplicate the problem. Fortunately, she was very specific in her description of the problem. She stated that once or twice per day her Maxima's engine would not turn over when the key was turned to crank. She also noticed that at the same time all the dash lights would go out and the dome lamp would not operate, (if the door was open), as well. She added that if the key were turned on and off 5-6 times the car would start normally and then be fine for the rest of the day.
The customer's report of turning the key several times to correct the problem made me wonder if the ignition switch could be faulty. I went over to start the car to move it and it started fine. I figured I should start with a check of service bulletins then a printout of related wiring diagrams.
A note of caution here: Recently we were shocked to learn that our CD-ROM database no longer contained any bulletins for Nissan newer than Dec. 1997. Further investigation by yours truly revealed that we were two years behind on BMW, Mazda, and Subaru TSB's as well. Keep in mind that these manufacturers have no longer been releasing technical service information to independent publishers like Alldata and Mitchell. Personally, I believe it is the beginning of a quest to squash us out as independent service providers. The EPA is mandating that manufacturers release all "emission relevant" service information. That's nice, but emission TSB's are only a minute part of all the service bulletins that are written. Motor Age has featured several articles on this issue. I would recommend all independent service providers read these articles to stay abreast of this very important issue.
Anyway, with the dated information we had on Nissan, there were no relevant bulletins that pertained to this car's symptoms. A scan tool connect did not reveal any fault codes. It was time to study the wiring diagrams. While our computer was printing the wiring diagrams for the dome lamp, dash warning lamps, and starter circuit, I went back to the car to see if it would start. Bingo! As I tuned the key to crank their was the "click" of a relay in the dash somewhere below the radio and then all the dash warning lamps went out. The car would not start. On a hunch I rapped the right hand side of the center dash leg near the radio and the dash lights lit up and I was able to start the car. Now the car was starting on every attempt. I began to wonder if a relay or component in the center dash was problematic and my hitting the dash shocked the faulty item back on-line. I decided to check IATN's E-Mail Archives for similar problems on this model. (For those of you who don't already know, IATN has a nice web site for problems that are not common enough to warrant the auto manufacturer to write a tsb. We pay a small monthly fee to IATN which allows us to look up any problems and solutions reported by other technicians for a given make and model). Unfortunately, I did not find any relevant E-Mails for this problem. Before digging into the dash on this car I decided to run these symptoms by our tec-line. The representative at the tec-line had reported experiencing other Nissans with similar symptoms. They recommended testing the inhibitor relay. With the inhibitor relay removed the engine would not crank but the dash lights worked normally so we ruled this out as a cause of the problem. They also recommended testing the speed control module since it can keep the dash warning lamps out and because it is under the radio and adjacent to where I hit the dash. We pulled the radio and center console trim plate to access the speed control module. Referring to Figure # 1 and #2, this looks like a big job but is actually fairly simple. The hardest part is trying not to damage the optional woodgrain trim plates. We left the dash apart and awaited our next "no crank". Approximately two hours later we attempted to start the car and again the car would not crank. We tapped the speed control module but the car still would not crank. After several tries the car started. We disconnected the speed control module and found that it killed the dash warning lamps but being disconnected did not prevent the car from cranking. Feeling as though we had been chasing the proverbial wild goose, it was time to study those wiring diagrams.
Looking at the dome lamp circuit in figure # 3 we can see how power is supplied by fuse # 26 and that the ground is supplied by pin # 5 of the BCM. The BCM should apply a ground for the dome lamp if any of the door switches are reporting a ground at pin # 21 of the BCM. There is no evidence of any relationship to the starter circuit or dash warning lamps here. Looking at the starter circuit in figure # 4 and #5 we can see that power makes its way to the starter from fusible link D through the ignition switch, then through the inhibitor relay to the starter solenoid. No visible connection to the dome lamp or dash warning lamps here either. Finally, referring to the wiring diagram for the dash warning lamps in fig. # 6 there also does not appear to be any evidence of a connection to the starting circuit or dome lamp. Actually, looking back at Figs. # 3 and # 4 they do have one item in common. It appears that they both get their fused power from the positive battery cable. Well, so what. Everyone knows that when the engine is off that the positive battery cable is the source of all power. Did I say positive battery cable or positive battery cables? Notice at the top of Figs. # 3 and # 4 that they appear to source power from a single one wire connection to the battery. Both diagrams have a note that says "Refer to EL-POWER". Well, lets look at the EL-POWER schematic. The EL-POWER schematic is a ten page diagram. Looking at the first diagram of the EL-POWER schematic, Fig # 7, we can see that the positive battery cable actually branches off into three separate directions. The large positive cable (actually not shown in Fig # 7) goes directly to the starter. Two separate W/R wires come right off the positive battery cable and go to the fusible link box. These wires feed the starter solenoid and the fusible links that power the dome lamp and dash warning lamps. Technically, if these two smaller wires were compromised the vehicle would not start and power would not get to the dome lamp and the dash warning lamps. These two wires connect at a red plastic junction at the positive battery terminal. We have heard of this being a "Nissan problem" on older Nissan's but have never witnessed it ourselves. We back probed one of these wires with our voltmeter and waited until the next time the car would not crank. Finally at the end of the day, the car would not crank. All the dash waning lamps were off and the dome light was out. Taking a look at figure # 8 you can see that we have battery voltage at the main connection at the battery. Now looking at figures # 9 and # 10 we can see that the smaller positive W/R wires only have 3.5 and 3.7 volts respectively. This red connector was now hot to the touch. Knowing that heat is a sign of resistance we cut the connector open. Clearly in Fig. # 11 you can see the heavy corrosion that was inhibiting all the power from flowing down these smaller wires. After checking with Nissan we found that this "sub harness" assembly was priced over $ 300.00. Since this connection is not a fusible link or fuse, the customer decided to forgo the Nissan subharness and have us install a universal battery terminal. Fig. # 12 shows the completed repair.
Some of your Nissan customers may get confused when attempting to
jump start their cars since Nissans' negative battery cable is black with
a red stripe. That combined with the fact that we no longer had the red junction
box at the positive battery terminal, we decided to paint two red plus signs
on the battery so there would be no mistaking connections in the future. In
closing, we would like to mention that we have seen Nissans that have been
jump started in reverse polarity. In the case of a Nissan Sentra we repaired,
both the alternator and the radio suffered unrepairible damage. Quite an
expensive repair due to jump starting the car incorrectly. Forewarned is