97 Honda Passport - persistent P0352

Schematic for ignition can be found at BBBind.com. See trouble codes this forum for causes/solutions. 12v on primary and a trigger to ground from control module fires coil. Can use noid light attached to circuit connector to see if control module/wiring good.

Thanks very much for the help. Borrowed noid light set from local parts store. Had no idea which fuel injector type Passport uses. Only one noid light fit (GM PFI), so used that one. The coil connector has 3 terminals (3 wires). So there were two ways the noid could attach. The excellent TC description mentions two wires. So initially a little confusing, but not a big deal. #1 cylinder tests - learn normal results Removed connector to coil (left front). Tried noid light both different ways (1+2 or 2+3). One of the ways (2+3) worked (noid light blinks). Hard to tell if blinking or steady, I guess blinking. Connect multimeter black wire to battery negative. Connect red wire to a coil connector terminal. Terminal #3 is steady 12 volts (actually 14.6) Terminal #2 (middle) is 17 AC Hz (driver wire) Reconnect coil after tests #3 cylinder tests - double check normal results Removed connector to coil (left middle). Ran same tests as above, got same results. For some reason, the driver wire said 15 Hz. Reconnect coil after tests #2 cylinder tests - find the fault Removed connector to coil (right front). This is the cylinder that is not working correctly. Noid light does NOT light up or blink. 100% dark. Terminal #3 is steady 12 volts (actually 14.6) Terminal #2 (middle driver wire) is 1-2 Hz AC. At this point, I know coil #2 is OK. I already knew that from switching coils. Problem seems wires going to #2, or bad PCM. The wiring harness seems difficult to check. The wires go between engine sections, cannot be followed. The wires quickly merge into larger wire bundles. If I could find the other end, I could check for continuity. Finding the other end seems pretty difficult. The PCM is called part of an ECM on Honda Passport. ECM is maybe under the middle of dashboard, but not sure. Any advice on what to do next? Anyone know where coil #2 wires come out, to check continuity? Anyone know exactly where the ECM / PCM is? 4S6CM58V8V4401488 is the VIN Thanks, Daniel

PCM- look inside cabin,center below dash, forward of shift lever. Check bbbind.com for electrical schematic for coil to PCM pinout. The trouble codes section of this forum has a good info on isolating P0352.

Thanks for confirming where the PCM is. Very easy to access. Lots of wires (about 96)! And just has numbers, does not label the banks (A, B, C, etc.). However, turns out I do not yet test at the PCM (see below). /////////// So far, from trouble codes section of forum: Causes ruled out for sure: - Bad Coil (COP) (noid light is dark) (switched coils) - Loose connection at coil or broken connector locks (noid light is dark) Cause I think is ruled out, but not sure: - Open on COP driver circuit (I see 1-2 Hz AC from multimeter) Possible causes remaining: - Short to voltage or ground on COP driver circuit - Faulty Powertrain Control Module ////////////// Checked bbbind.com and IMO it does not have enough detail. It does not show the wires from PCM to coils (or I missed it). Luckily, my library system scanned a few pages from the 1997 Passport service manual and it has great detail for the circuits and connectors. It’s really incredibly great. The service manual shows the PCM does not directly connect to the coils. Instead, there is a “coil driver box” in between. After a bit, I figure out it has 3 connectors attached (E34 with 5 wires in, E35 with 3 wires in, and E36 with 6 wires to the 6 coils). Looking around the vehicle, right on top of the engine, close to the windshield, I find the "coil driver box". About 3 x 3 inches flat black square, two bolts, three connectors as in the manual. I check continuity for green/black wire running between position 2 on cylinder #2 coil and position 6 on the "coil driver box" E36 connector. Zero resistance, so rule out open circuit in coil driver wire. Next, keeping one lead on E36 position 6 at the "coil driver box", I touch the other lead to various positions on the 3-prong coil connector for cylinder #2. Infinite resistance for 1 and 3 positions, still zero resistance for position 2, so rule out short in coil driver wire. I think it very unlikely the driver wire is shorting to another wire or metal surface, because all the wires are strongly wrapped into bundles. At this point, it seems either “coil driver box” or PCM is bad. My guess would be the "coil driver box". Looking at some parts web sites, it is officially called SWITCH ASSY., IGNITION COIL POWER - 8161982390 = 8-16198-239-0 part. It costs around $130 new. Anybody know about the "coil driver box"? Any way to test it? Certainly seems likely that might be the problem. Any advice on what to do next? Thanks

Maybe compare the inputs to the coil driver box from the PCM? Is there separate ion sensing module? Sorry don't have much else at the moment. Let us know the outcome.

I would like to compare the inputs to the coil driver box with something. The problem is that I do not have the foggiest notion of what kind of comparison to do. The detailed wiring diagram from the service manual shows exactly what connects to what, but does not indicate the functionality. According to the librarians, the service manual does not explain how to troubleshoot the coil driver box (or the PCM). I suppose I could look for continuity, but it seems a bit of a shot in the dark, and I fear a little that I might damage an internal circuit. No, there is no ion sensing module that I can see. Thanks for your help. I'm going to call around and see if I can find a salvage coil driver box.

Regarding the inputs to the coil driver box. I was thinking you could test input much like what was done for the output only the input signal would be at a lower level( 5v square wave). The circuit between the PCM and the ignition control (IC) module is monitored for open circuits, shorts to voltage, and shorts to ground. As long as you don't short any of the IC inputs to ground the PCM would be safe. In addition best to verify circuit good between IC and PCM. If there is a short/open it would effect PCM trigger circuit.

Summary: I replaced coil driver box and vehicle works perfectly now. I ended up not testing the coil driver box. I knew there was a problem with the output to coil #2. But the nature of the inputs was unclear. It sounds like you are saying the purpose of the coil driver box is to up the voltage from 5 V to 12 V. Maybe so, I don't know. I ended up deciding to try swapping out the coil driver box. The only other choice was swapping the more expensive PCM. The coil driver box was very difficult to find online. The few I found were around $140 plus shipping. My wife was getting impatient, did not want to wait longer to fix it. She argued to just pay the $150 to get an emissions test waiver. My explanations of what I was doing went totally over her head, just frustrated her. The Honda dealers did not have the part, or know anything about it. Understandable. The car is old. It's really an Isuzu. No Isuzu dealer around here. The part is really a GM part. I ended up calling around to salvage yards. A few salvage yards suggested I would be able to find the part. The suggested prices varied wildly. It seemed like if I wanted to I might get it for virtually nothing, but I did not press the issue. Also, it seemed they would charge about the same for the coil driver box (very simple part) as the PCM (the computer). Anyway, I picked the closest one, and headed off in the Passport. This was an experience. Two heavily tattooed males were very busy at the counter. A short buxom lady apparently did the bookkeeping. A lonely looking dog sniffed at each customer as they entered. Odd parts lay about all over. Incredibly junky. My victim, a 1996 Passport, was at C9 in the yard. Tool pail in hand, I wandered around the lot a fair amount. There were no markers. I had received verbal instructions. Finally, after taking the scenic route, I found the junk vehicle. Another junker was stacked on top of it. They were both in *** terrible *** shape. But the coil driver box was there, looked shiny, and luckily was easy to get to (no hood). Almost any other part would have been *** extremely *** dangerous to extricate, because of the other car stacked on top. To me, the salvage part looked identical, and the numbers matched on one side. Back inside, the tatooed guy at the counter said it seemed a different part, because the numbers did not match on the other side. He suggested ten bucks, no warranty. I happily paid. I swapped the parts in the parking lot. Takes about one minute, very easy. Cleared the codes. Started the vehicle. Check engine light is off!!!!!!! The difference in the engine feel and sound was dramatic. Before, it vibrated. Now, it was smooth. A day later, after driving the vehicle around a lot, it passed the emissions test. WA state allows two fails on the I/M ready test, EVAP and another. Finally through some combinations of driving, highway, and overnight sitting, the computer decided that things were OK. It took longer for the cycle to run that I expected. My OBD-2 reader is really cool. It beeps while driving, letting you know the current I/M ready pass / fail status. You can see the status change over time, as the cycle runs. Thanks again for all the help. I probably couldn't have made this work otherwise. And no repair shop was going to do this for any reasonable amount. They just wanted the $150, do no work, sign the waiver.

Thanks for the wrap up. Good call, what luck on finding the coil driver at that price. Maybe you should go back and get the PCM . Enjoyed the narrative of your junk yard experience. Keep that Isuzu running!