A couple of years ago I removed the instrument cluster and resoldered the suggested joints and the issue I was having at the time with the instrument cluster and gauges not working was resolved.

At present I am having similar but distinct issues.

First of all I have a 1998 Dodge Caravan. It has the 3.0 Liter engine.

I am having 3 problems. 1). The temperature guage on the dash does not work nor show any movement after the engine has warmed up. 2). Both engine cooling fans start to run from the very beginning when the van is started. 3). The van is very hard to start when it is cold outside. We just moved from Southern Texas to northern Texas (Amarillo). When we lived in Laredo, I the van always started right away. Now it takes a lot of pumping of the acerator and finessing of the starter to get it to start.

Comments on what could be the problems(s)? Are all 3 of these problems interrelated?

Thanks for your input ahead of time.

Dennis.

 

I tested the engine temperature sensor this afternoon. I got the following readings: Before, when engine was cold: approx. 13,000 ohms; after, when engine had warmed up: approx. 1000 ohms.

I would like to test the wire(s) from the sensor to the instrument cluster. Maybe I am looking at a faulty wire from sensor to PCM and instrument cluster.

Any thoughts or suggestions?

dennis

 

Post #3
According to my Haynes manual, the readings I posted above are within tolerances. Most importantly as I understand things,5 there is a large difference between the cold and warm readings.

More data to share from today:

I checked the wire from the ECT (Engine Coolant Temperature Sensor) and the PCM (Powertrain Control Module) and I had a good, strong reading via my ohms meter. I also checked the wire from the ECT and the MAP connection and had a good, strong reading vial my ohms meter.

I also checked the current with the van running to the back of the the instrument cluster (red plug) on the dash and received a approx. 2.5 volt reading.

I am trying to address one problem at a time, with the temperature guage on dash being the most important at present. With voltage to red plug reading 2.5 votes, is it safe to say that problem of an inoperative temperature guage lies in instrument cluster?

One more piece of data to add to mix: the van is very hard to start but once started and warm and then turned off, it starts right up.

 

Hold the trip and reset ***** in on the cluster then turn the key to "on". The cluster will start a test cycle and the temp gauge should move. If it doesn't replace the cluster.

 

"Hold the trip and reset ***** in on the cluster then turn the key to "on". The cluster will start a test cycle and the temp gauge should move. If it doesn't replace the cluster."

Cougar41....Thank you so much for taking the time to share your insight.

I conducted the test as you stipulated. And temperature gauge did move up and down as instrument cluster self test was conducted. I am now assuming the problem is not in the instrument cluster.

I want to reiterate what is happening, other than the engine temperature gauge not registering a reading. 1) Engine cooling fans come on as soon as engine starts, no matter how cold engine and outside temperature is. 2) It is very hard to start engine when it is cold. I have to pump accelerator a lot and work starter hard until engine will catch and remain running. Process of late has taken 1 minute or more.

I have not tested the MAP sensor...I do not know the proper procedure. Could the MAP sensor be the cause for all of this, including the engine temperature gauge.

Could someone be kind enough to share with me the proper MAP sensor testing procedure?

Also, and I am directing this question to you Cougar41 especially, what resource or manual do you use? I wish I would have had the resource you referred to with the instrument cluster test a week or so ago when the instrument gauge problem first arose. I would like to make the investment in the manual or resource you use.

Thanks ahead of time for your help here.

 

I have the Haynes manual but the MAP sensor and it's' 3 prong, inline arrangement/assignment is not covered.

 

To be honest I don't use a manual much. I have a Haynes manual I shake the dust off of from time to time. I use the free EBSCO library data base mainly for wiring diagrams, TSB/recall info or other listed info. The bulk of the info I post comes from gleaning information from 6-8 automotive forums on the web over the last 8 years. The term forums junkie fits me to a T since I read them nearly every day. I've learned where info can be found and refer to those websites frequently. Working on my van and a few others over the last 15 years forced me get educated in a hurry, though I haven't done much of that in several years.

An example? That instrument self test procedure can be found in many places but the complete factory manual procedure is listed on this forum at this link: https://dodgeforum.com/forum/dodge-c...rmation-2.html Read post #16 titled "DIAGNOSIS AND TESTING - SELF-DIAGNOSTICS". That post is only one of many very useful posts on that multipage thread.

> MAP procedure? http://easyautodiagnostics.com/chrys...shooting_1.php
> Cooling fans? The majority of the time the radiator cooling fan relay is the culprit.
> Hard cold starts? If it start hard on the first start of the day but starts fine later there's a good chance fuel pressure leaking down. That could mean a visible fuel leak, leaking injector or leaking regulator or pump. If it starts hard all the time it could be that or any number of causes.

 

Cougar41: thanks again for all your input!

If you had my van and had these 3 distinct problems that you are trying to resolve (no dashboard temperature gauge, hard start in the mornings and engine cooling fans running continuously from engine start, you would treat them as 3 separate problems it appears...and none are inter-related...???

I brought up the MAP sensor because I was hoping it could be the malfunctioning part and finding it defective would solve one or more problems when replaced.

My big goal here is to only replace the defective part(s) and not use the typical scattered approach that so many of us use.

Thoughts anyone?

 

I don't think I have a bad MAP sensor. I do not have any of these bad MAP symptoms:

1). Bad gas mileage

2). Black smoke coming out of the tail pipe, especially when you accelerate the vehicle.

3). No power and/or hesitation as you accelerate the vehicle. It feels like all of a sudden someone cut the power out momentarily as you step on the gas to get the vehicle moving.

Comments?

 

Does my 98 Dodge Caravan with a 3.0 Liter engine have a just an ECT (Engine Coolant Temperature) sensor or is there a coolant temperature sending unit as well?

In other words, where does the signal come from that operates the temperature as shown on the instrument cluster/interior dashboard engine temperature gauge?