Okay bit of a head scratcher here. 1994 D1 with distributor setup.

A few weeks ago I was off roading. In the parking lot after 3+ hours of trails I was letting the truck idle while I refilled tires. It coughed and cut out, then would not restart. No spark to the plugs that I could see. A friend said he could hear the fuel pump running but now I'm not so sure.

I suspected it was an issue with my old distributor. Looked original to the car and something was rattling inside there. I replaced the distributor along with the timing chain "while I was in there". Buttoned everything back up and still had the same issue. Engine cranks, dashboard lights up, but no action.

Some diagnosis has revealed I'm not getting any voltage to the fuel pump connector AND I'm not seeing any voltage to the ignition coil.

For the fuel pump: I've replaced the old aluminum fuel pump relay and the inertia switch. Connector at the pump looks good. Fuel pump itself was replaced a year ago. I'm not seeing any voltage at the new inertia switch in any key position which I believe is the go-between for the relay and the pump itself

For the ignition coil: The white/green and white/black wires going to the coil from the loom (which I think tracks back to the ECU) aren't carrying any voltage in any ignition position. I replaced the other aluminum relay (I think known as the main relay) which I think controls the system. Coil is about a year old. Checked all the grounds near the relays I think they are good.

In addition to the above I have also purchased a replacement (used) security system/immobilizer unit as I've heard that can be an issue. The used one I guess could also be junk but not sure how likely that is...

Any ideas for next steps? I just can't believe it is possible that both the fuel pump and ignition wires could fail at the same time. Is there something upstream I should try? Maybe ECU itself has gone bad, or the ignition switch in the steering column?

Oh one last thing. It recall that before all this trouble I used to be able to hear a relay/relays "drop out" about 5 seconds after turning the ignition on. I'm not able to hear that anymore. I wonder if that means the new relays I've swapped in are just quieter or something is not happening as it should.

Thanks in advance for any help!

 

Hey there 94Disco1,

I'd go over your grounds again. This time pull them off and attack them with a wire brush. Make em shine, then do the same for the mounting location and any bolts that connect the grounds. Do that and report back.
Good Luck.

 

Alright I'm back with updates.

Tumbler, just to start - thanks for the lone response to this post lol. I've now gone over all the grounds I can find, including doing a real cleanup job on the ones around the footwells on both sides. Doesn't seem to have done the trick.

To recap, when I turn the key the engine cranks. Fuel pump relay does not get energized. Main relay does not get energized. The main issue at this point is I'm not seeing 12volts at the coil, nor am I seeing 12volts at Pin 19 of the ECU. Supposedly these both should be energized when the key is placed in the "run" position. Since Pin 19 of the ECU is not getting voltage, my relays will not be energized...consistent with what I'm seeing.

I've replaced the ignition switch/key assembly just to be sure. The new ignition switch is correctly sending 12volts out when placed in the run position through a thick green wire.

My mind is currently in two places:
1 - The wire that carries 12v from the ignition switch to the coil and ECU Pin 19 is broken somewhere behind the dash
2 - The AMR2109 alarm ECU is somehow preventing the coil and ECU Pin 19 from seeing 12volts

For hypothesis 1, I can confirm I have continuity between ECU Pin 19 and the positive side of the coil. Does anyone have any idea where the ignition wire "splits" and feeds the coil and ECU?

For hypotheses 2, as mentioned last post I did purchase a used replacement AMR2109. When I plug it in, the alarm outputs seem to get triggered (alarm relay and flashers start to go off) so I don't think I can trust the replacement. Or maybe some condition is present that is correctly setting the alarm off but my old one is messed up? In either case I could do the 1994-1995 alarm bypass trick. However when I read those threads I'm not clear on the issue folks see is a failure to crank or a failure to fire.

Any advice is appreciated!!

 

Another update. I've now bypassed the alarm module and car still will not start. For anyone interested when the alarm module is tripped/removed entirely the starter is prevented from engaging. My condition is that the starter works but the key/ignition is not powering the coil and not sending power to ECU pin 19 (which is connected to main and fuel pump relay) so it cranks but no spark. I thought there was a change the alarm box was malfunctioning and prevented the coil/ECU pins from getting power but that is not the case....

Okay so the lone remaining possibility seems to be the key/ignition 12volt source to the coil and ECU pin 19. I've been pouring through all the diagrams I can find and the 1995 electrical troubleshooting manual but the wiring chase and connectors are not shown. From my spelunking efforts, there is a fat green wire that runs from the key/ignition which sees 12v in "position 2" but it disappears far behind the dash. From what I can tell it does not reemerge behind the RHD passenger footwell. Somewhere it must connect to the wires feeding the positive side of the coil and pin 19 of the ECU, but I am really struggling to find it.

Does anyone have any domain knowledge here?

Thanks
Ryan

 

You have clearly gone farther in your diagnostics than i did when i had a similar problem with my 98. I had a ton of recommendations, "Alarm" "Crank Position Sensor" "ECU". Mine was the main relay in the engine bay. The black one on the Captain's side fender. I think you said you checked that, but it might be worth swapping it anyway.

 

Alright figured my issue(s) out I think. My right hand (passenger for NAS) footwell has a rust hole in the body which allowed water to ingress into the relay harnesses. That, paired with some corrosion on the relays must have caused Fuse F3 on Satellite 1 to become overloaded and blow. When I was in the parking lot after it initially stalled out I believe I actually replaced F3 and one or two others in the fascia fuse box, but it must have blown immediately after due to continued shorting/water ingress so I never checked it again. In chasing the ignition wiring from the battery back to the ignition switch and then onto the coil and ECU I found F3 again and replaced it successfully. I've also replaced all of my relays in the right hand footwell and will be patching the body hole soon.

I was able to use the 1995 Electrical Troubleshooting Manual to help in chasing the wires, but honestly it is very difficult to read (worse in my opinion than other ETMs) and has at least one mistake in it as far as I can reason. For that reason I drafted my own very simplified composite diagram to help me map out the components involved in a "no start" situation. Maybe it will be helpful for the next person... Any suggestions for improvement are welcome.