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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Ford
Satisfied Customers: 2637
Experience:  AA in automotive Technology, 15+ years in the trade
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Curious while browsing through 1988 2.9 ford ranger problems

Customer Question

curious while browsing through 1988 2.9 ford ranger problems I noticed Amede ? seemed to understand wiring issues, maybe everyone there is. I am in need one someone very well versed?
Submitted: 11 months ago.
Category: Ford
Expert:  AMEDEE replied 11 months ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. Does the check engine light come on with the key on? Does it og off while cranking? Both are very important. Both the yellow wires going into the ignition switch should have power at all times. Then the red/light green wire should have power leaking the switch with the key in the "run" position.

Expert:  AMEDEE replied 11 months ago.

You can also run a few voltage checks on the system. There should be 5 volts going to the TPS with the key on and there should be battery voltage on the red wire going to the idle air control motor with the key on.

Expert:  AMEDEE replied 11 months ago.

Please run these checks/tests and post back with your findings. I do work all day today but will be back on line later tonight. I will be looking forward to your reply!

Customer: replied 11 months ago.
Thanks Amedee, Check engine light on KO, cranking it goes out, yellow wire at switch 12 volts, R/grn wire 12 v in run only, TPS 5 v KO, IAC 12v KO. Steve
Expert:  AMEDEE replied 11 months ago.

Thank you for checking these for me. Do you know if the engine has injector pulse while cranking?

Customer: replied 11 months ago.
I have not checked with noid light
Expert:  AMEDEE replied 11 months ago.

Ok, no problem. Lets check the power going to the ignition coil and ignition module. Backprobe the Dark Blue wire at the ICM connection and check the circuit for voltage. It should indicate greater than 9.0 volts or less than 1.0 volt. If the voltage is high, tap it to ground simulating an RPM signal and listen for the fuel injectors to trigger, the fuel pump relay to activate, and the coil to trigger indicating a defective distributor pickup coil. If the voltage of the circuit is low, induce power into the circuit through a standard 12-volt test light and check for the same activity from the fuel injectors, coil, and pump relay, indicating a defective pickup coil. If the described activity does not occur when the circuit is tapped to ground or power through the test light, check the DB wire for a short to ground in the harness between the ICM and the PCM connections.

Expert:  AMEDEE replied 11 months ago.

Here is a wiring diagram of this circuit.

Customer: replied 11 months ago.
I had 10.6 v at blue wire, triggered it to ground, it picked up relay and sounded like injectors. DB wire is not grounded. I have rebuilt dist. with new pick-up, new ignition mod., cap and rotor, then after still not starting switched it with one I removed from my running 2.9. which still runs fine. I have also switched coils.
Customer: replied 11 months ago.
Red wire at coil has power, I had also disconnected suppressor to make sure it was not grounded. Tach side wire does not pulse clearly with test light as running ranger does.
Expert:  AMEDEE replied 11 months ago.

Hello and sorry for the delay! Did you say there is fuel pressure when cranking? Does the engine have spark if you pull the spout connector and restest for spark?

Expert:  AMEDEE replied 11 months ago.

I suspect you may have a wiring issue going to or coming from the distributor. Check for a ground signal trigger going to the ignition coil on the (Dark Green/Yellow (DG/YL) wire) with a test light connected to battery positive and check for a trigger signal when cranking. If no trigger signal is present, check the same circuit for a trigger signal at the Ignition Control Module (ICM) with the ICM and coil connected.

Expert:  AMEDEE replied 11 months ago.

I do work again until late tonight. I will be on line after work and tomorrow morning before work. I will be looking forward to your reply!

Customer: replied 11 months ago.
40 lbs. fuel pressure, no spout connecter, no spark. From dg/y on coil and at ICM key off test light to battery positive lights and triggers start relay, key on, nothing; start cranking, nothing; after cranking stops, dim light and 1 bigger flash then nothing. During coil and ICM tests I had forgotten to replace spout connecter, if it matters.
Expert:  AMEDEE replied 11 months ago.

So your saying that the spout connector was disconnected during this test?

Customer: replied 11 months ago.
Customer: replied 11 months ago.
It tests the same with spout connecter in.
Expert:  AMEDEE replied 11 months ago.

Ok, if there is no signal coming from the ICM, then the new ICM is either bad or there is a wiring issue going to the ICM or coming from the ICM. Be sure to inspect the wiring harness very close and check for a good ground going into the ICM.

Customer: replied 11 months ago.
OK, I've tested grn/y wire from ICM to unplugged coil, it has continuity and is not grounded. From ICM to unplugged pin 4 on ECA on 200k ohm scale reading is 21.9 and not grounded. Blk wire at ICM has continuity to pin 16 at unplugged ECA and is not grounded.
Expert:  AMEDEE replied 11 months ago.

Does this ignition module get held in place by a few screws?

Customer: replied 11 months ago.
Plugged in to ICM Blk wire has continuity to ground and numerous other wires at unplugged ECA.
Expert:  AMEDEE replied 11 months ago.

Well, I got some bad news. I am all out of ideas. I will leave this question open for other experts. Good luck!

Customer: replied 11 months ago.
this grey ignition module gets held in place by 2 screws. I am sure this is an operating distributor. I've also tried a jumper wire from neg battery to dist.base. Thanks anyway.
Customer: replied 11 months ago.
OK Amede, give me an idea of your analysis before signing off on this. Does everything test ok to run. I've stripped the wiring harness from the computer thru engine compartment up into and removed speedometer and gauges. I'm thinking if distributor is sending signal it is getting robbed some where. Tell me what you do know about this issue.
Expert:  K. Wiggins replied 11 months ago.

Hello, new expert here, I've got a few things for us to run through to check the ignition system. I will pst them below.

Also checkthe wiring around the coil, ifit's in convulted tubing, which it should be remove it and examine the wires closely. The tubing being on them was actually due to a service bulletin from ford and they may have rubbed some on the coil bracket before the bulletin was carried out.

Let me know what you find and we can work further.

Customer: replied 11 months ago.
Hello expert K. Wiggens, Thanks for jumping on board. I have switched coils with a running same year,1988, same engine,2.9, didn't help.
Expert:  K. Wiggins replied 11 months ago.

Thanks,didall the voltage andcontinuity tests between the TFI plug and ecm show good as well?

Customer: replied 11 months ago.
I changed the plug end at the ignition control module.
Customer: replied 11 months ago.
Well actually I have not checked voltage between pins at the computer . Probably between blk. and wire that also goes to coil , tach side, from ICM.
Expert:  K. Wiggins replied 11 months ago.

Run through those checksI posted earlier, they should narrow it down to the culprit.

Customer: replied 11 months ago.
Alright K, I've tested for voltage at ECA with key on between blk wire pin 16 ig. grd. and pin 4 dkgrn/y ig mod, 8.4V; 16 and pin 36 spout .68V 16 and pin 56 pip 8.39V.